Product Description
Product Name
American Type Hose Clamp
Product Parameters
| Item(Small American Type) | Model | Brand width(mm) | Thickness(mm) | PCS/Bag | PCS/BOX |
| CZX-CLA-001 | 6-12mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-002 | 10-16mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-003 | 13-19mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-004 | 16-25mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-005 | 19-29mm | 8 | 0.6 | 100 | 5000 |
| Item(large American Type) | Model | Brand width(mm) | Thickness(mm) | KG/100PCS | PCS/BOX |
| CZX-CLA-001 | 14-27 | 12 | 0.6 | 1 | 2000 |
| CZX-CLA-002 | 18-32 | 12 | 0.6 | 1.3 | 2000 |
| CZX-CLA-003 | 21-38 | 12 | 0.6 | 1.55 | 2000 |
| CZX-CLA-004 | 21-44 | 12 | 0.6 | 1.61 | 2000 |
| CZX-CLA-005 | 27-51 | 12 | 0.6 | 1.7 | 2000 |
| CZX-CLA-006 | 33-57 | 12 | 0.6 | 1.8 | 2000 |
| CZX-CLA-007 | 40-63 | 12 | 0.6 | 1.9 | 1500 |
| CZX-CLA-008 | 46-70 | 12 | 0.6 | 2 | 1200 |
| CZX-CLA-009 | 52-76 | 12 | 0.6 | 2.2 | 1000 |
| CZX-CLA-571 | 59-82 | 12 | 0.6 | 2.36 | 1000 |
| CZX-CLA-011 | 65-89 | 12 | 0.6 | 2.5 | 800 |
| CZX-CLA-012 | 72-95 | 12 | 0.6 | 2.6 | 800 |
| CZX-CLA-013 | 78-101 | 12 | 0.6 | 2.7 | 700 |
| CZX-CLA-014 | 84-108 | 12 | 0.6 | 2.75 | 600 |
| CZX-CLA-015 | 91-114 | 12 | 0.6 | 2.8 | 600 |
| CZX-CLA-016 | 105-127 | 12 | 0.6 | 3 | 600 |
| CZX-CLA-017 | 118-140 | 12 | 0.6 | 3.4 | 500 |
| CZX-CLA-018 | 130-152 | 12 | 0.6 | 3.5 | 500 |
| CZX-CLA-019 | 141-165 | 12 | 0.6 | 3.7 | 500 |
| CZX-CLA-571 | 155-178 | 12 | 0.6 | 4 | 500 |
| CZX-CLA-571 | 175-197 | 12 | 0.6 | 4.3 | 400 |
| CZX-CLA-571 | 194-216 | 12 | 0.6 | 4.4 | 400 |
| CZX-CLA-571 | 213-235 | 12 | 0.6 | 4.9 | 400 |
| CZX-CLA-571 | 232-254 | 12 | 0.6 | 5.3 | 400 |
| CZX-CLA-571 | 251-273 | 12 | 0.6 | 5.6 | 400 |
| CZX-CLA-026 | 270-292 | 12 | 0.6 | 6 | 400 |
| CZX-CLA-571 | 289-311 | 12 | 0.6 | 6.2 | 400 |
| CZX-CLA-571 | 100 | 12 | 0.6 | ||
| CZX-CLA-571 | 200 | 12 | 0.6 | ||
| CZX-CLA-030 | 300 | 12 | 0.6 | ||
| CZX-CLA-031 | 350 | 12 | 0.6 | ||
| CZX-CLA-032 | 400 | 12 | 0.6 | ||
| CZX-CLA-033 | 450 | 12 | 0.6 | ||
| CZX-CLA-034 | 500 | 12 | 0.6 | ||
| CZX-CLA-035 | 550 | 12 | 0.6 | ||
| CZX-CLA-036 | 600 | 12 | 0.6 |
| Product name | stainless steel clamp(201,304,316 is optional) |
| Features | Exquisite workmanship, no rust |
| Product properties | see parameter table |
| Product color | Stainless steel color |
| Product material | Authentic stainless steel all steel (including screws) |
| Product Specifications | Various specifications (various sizes can be customized) |
| Product Usage | Widely used in stainless steel, wire and cable, new energy vehicles, hoses, ships, chemicals and other industries |
| The hose clamp is relatively small and its value is relatively low, but the role of the hose clamp is huge. American hose clamp, also known as clamp. American stainless steel hose clamps: divided into small American hose clamps and large American hose clamps. The width of the hose clamps is 12.7mm and 14.2mm respectively. Using through-hole technology, the hose clamp has a wide range of applications. It is suitable for fasteners for connecting soft and hard pipes with a thickness of 30mm or more. The appearance after assembly is beautiful. Features: The worm has low friction, which is suitable for middle and high-end vehicles, pole-holding equipment or the connection of anti-corrosion materials. | |
| American type hose clamp: divided into 2 types: iron galvanized and stainless steel. The main difference is that the button pitch is perforated (ie through-hole button). The market is mainly made of stainless steel, which is mainly used in high-end markets such as auto parts and poles. The price Higher than the other two. | |
Detailed Photos
Product Application
Production Workshop
International Experiance
Certifications
After Sales Service
1.Reply in 24 hours.
2.In time response and professional suggestions.
3.Replacement product and tailor-made product both can do.
4.Small trial order accepted.
5.Certification, complete certificates,like CE, EU,Rohs, FDA.
6.Good quality and competitive price.
Contact Person
Celina Du
HangZhou Xihu (West Lake) Dis. Rubber & Plastic New Material Co., Ltd
/* January 22, 2571 19:08:37 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
Maintenance Requirements for Gear Couplings
Gear couplings, like any mechanical component, require regular maintenance to ensure optimal performance, reliability, and longevity. Proper maintenance can help prevent unexpected failures and downtime, leading to cost savings and increased productivity. Here are the key maintenance requirements for gear couplings:
- Lubrication: Regular and proper lubrication is essential for gear couplings. The coupling’s gear teeth and mating surfaces should be adequately lubricated to minimize friction and wear. The lubrication interval and type of lubricant used depend on the application, load, and operating conditions. It is crucial to follow the manufacturer’s recommendations for lubrication intervals and the appropriate lubricant to use.
- Inspections: Routine inspections should be performed to check for signs of wear, misalignment, or damage. Visual inspections can help detect any abnormalities, such as pitting, scoring, or corrosion on the gear teeth. Additionally, inspections can identify any misalignment issues that may need to be addressed to prevent further damage.
- Torque Monitoring: Monitoring the torque transmitted through the coupling can help identify any abnormal increases that might indicate a problem in the system. Sudden changes in torque levels could signal misalignment or other issues that need attention.
- Alignment Checks: Regularly checking and correcting shaft alignment is crucial for the proper functioning of gear couplings. Misalignment can lead to increased wear and premature failure of the coupling. Proper alignment reduces the stress on the coupling and connected equipment.
- Temperature Monitoring: Monitoring the operating temperature of the coupling can provide insights into potential problems. Abnormally high temperatures could indicate insufficient lubrication or other issues that need investigation.
- Coupling Removal and Cleaning: Periodically removing the coupling for cleaning and inspection of internal components can be beneficial, especially in harsh or dirty environments. This allows for a more thorough inspection and helps maintain the coupling’s performance.
- Replacement of Worn Components: If any components of the gear coupling, such as seals or gaskets, are worn or damaged, they should be replaced promptly to maintain the coupling’s integrity and prevent leaks.
- Proper Storage: If the coupling is temporarily removed from service or stored, it should be stored in a clean and dry environment to prevent corrosion and damage to the components.
It is essential to follow the manufacturer’s maintenance guidelines and recommendations for the specific gear coupling model being used. Regular maintenance and adherence to proper procedures can help extend the service life of gear couplings and ensure reliable and efficient operation in the mechanical system.
editor by CX 2024-05-16
China Best Sales High Quality Machinery China Factory Transmission Drive Roller Chain Coupling Gear gear coupling
Product Description
Welcome to Visit our wuyi CHINAMFG chain factory in CHINA.
all kinds of chain couplings, including as belows:
4012-4014-4016 ,,6018,6571,8018,8571,1571,12571 and so on.
| Item | Sprocket / plate wheel/gear | |
| Standard | DIN, KANA, ANSI, ISO, etc | |
| Material | C45, stainless steel SS304 & SS316, Cast iron | |
| Bore | Pilot bore, finished bore, taper bore | |
| Surface Treatment | Black oxided, Zinc plated, Electrophoresis, self color and so on | |
| Heat treatment | Teeth inductive and quenching hardened HRC45-50,High frequency quenching or no hardened | |
| Process | Forging, Cutting, Hobbing teeth, CNC Lathe machining | |
|
|
||
| European Type | 03B, 04B, 05B, 06B, 081B, 083B/084B, 085B, 086B, 08B, 10B, 12B, 16B, 20B, 24B, 28B, 32B,40B,48B with simplex, duplex and triplex | |
| American Type | 25, 35, 40, 50, 60, 80, 100, 120, 140, 160, 200, 240 with simplex or duplex and triplex | |
|
Double pitch sprockets Type |
C2042, C2052, C2062, C2082, C2040, C2050, C2060, C2080 | |
| sprocket Type | Taper bore sprockets,Finished bore sprockets,Idler sprockets with ball bearing,Double simplex sprockets,Sprockets with split taper bushings,Sprockets with QD bushings,Double sprockets for 2 single chains,Type A & Type B, Single, Double, Triple -all kind sof standardf sprocket or wheel plate,and also can match with special conveyor chain, agricultural chain. or can make , according to customer reuqiryment | |
| Business type | Manufacturer/FACTORY | |
| Main export market | Europe, South America, Southeast Asia, Middle East, Africa | |
| Manufacturing method | Forged and then machined and hobbed | |
Bitmap
|
Plywood Case/Pallet/cartons or according to customer reuqiryment |
| we are CHINAMFG chain factory from CHINA. |
| We make roller chains over 20 years. main ASA chains: — main DIN chains:06b-08b-10b-12b-16b-20b-24b-32b main motorcycle chains: H 520 520H 530 Our quality: middle level and good and stable. Follow up XIHU (WEST LAKE) DIS.HUA standard We also exported many industrial sprockets together with our chains. We mainly exported chains to South America AND Europe. |
/* January 22, 2571 19:08:37 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
Can Gear Couplings Be Used in Both Horizontal and Vertical Shaft Arrangements?
Yes, gear couplings are versatile and can be used in both horizontal and vertical shaft arrangements.
Horizontal Shaft Arrangements: In horizontal shaft configurations, gear couplings are commonly employed to connect two shafts in-line with each other. The gear coupling’s flexible design accommodates for slight misalignment and torsional movement between the shafts, making it suitable for various industrial applications. These couplings can handle high torque loads and are often used in heavy-duty machinery such as steel rolling mills, mining equipment, and conveyors.
Vertical Shaft Arrangements: Gear couplings are also well-suited for vertical shaft arrangements, where the connected shafts are oriented one above the other. In such cases, gravity can cause additional axial loads on the coupling, which gear couplings are designed to handle. The gear coupling’s capacity to accommodate both angular and axial misalignment is essential in vertical applications, where thermal expansion and contraction may induce relative movement between the shafts.
Whether in horizontal or vertical shaft configurations, gear couplings provide reliable power transmission and are widely used in various industrial settings. However, it is essential to ensure proper alignment and maintenance for optimal performance and to prevent premature wear or failure of the coupling.
editor by CX 2024-05-07
China factory Customized Giclz Type Coal Mine Machinery Drive Shaft Drum Gear Coupling Steel Internal Gear Coupling gear coupling
Product Description
Customized GICLZ Type Coal Mine Machinery Drive Shaft Drum Gear Coupling
Description:
A gear coupling is a mechanical device for transmitting torque between 2 shafts that are not collinear. It consists of a flexible joint fixed to each shaft. The 2 joints are connected by a third shaft, called the spindle.
Each joint consists of a 1:1 gear ratio internal/external gear pair. The tooth flanks and outer diameter of the external gear are crowned to allow for angular displacement between the 2 gears. Mechanically, the gears are equivalent to rotating splines with modified profiles. They are called gears because of the relatively large size of the teeth.
Gear couplings and universal joints are used in similar applications. Gear couplings have higher torque densities than universal joints designed to fit a given space while universal joints induce lower vibrations. The limit on torque density in universal joints is due to the limited cross sections of the cross and yoke. The gear teeth in a gear coupling have high backlash to allow for angular misalignment. The excess backlash can contribute to vibration.
Gear couplings are generally limited to angular misalignments, i.e., the angle of the spindle relative to the axes of the connected shafts, of 4-5°. Universal joints are capable of higher misalignments.
Product paramters:
Advantages:
1. Lowest price based on large scale production.
2. High and stable quality level.
3. Widely used in various mechanical and hydraulic fields.
4. Compensation for axial, radial and angular misalignment.
5. Convenient axial plugging assembly.
6. No brittlement at low temperature.
7. Good slippery and frictional properties.
8. Resistance to chemical corrosion.
9. Rich experience working with big companies in this field.
Packing & Delivery:
FAQ:
Q 1: Are you a trading company or a manufacturer?
A: We are a professional manufacturer specializing in manufacturing
various series of couplings.
Q 2:Can you do OEM?
Yes, we can. We can do OEM & ODM for all the customers with customized artworks in PDF or AI format.
Q 3:How long is your delivery time?
Generally, it is 20-30 days if the goods are not in stock. It is according to quantity.
Q 4: How long is your warranty?
A: Our Warranty is 12 months under normal circumstances.
Q 5: Do you have inspection procedures for coupling?
A:100% self-inspection before packing.
Q 6: Can I have a visit to your factory before the order?
A: Sure, welcome to visit our factory. /* January 22, 2571 19:08:37 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
Types of Gear Coupling Designs
There are several types of gear coupling designs available, each with its own specific characteristics and applications. The main types of gear couplings are:
- Sleeve Gear Couplings: Sleeve gear couplings consist of two hubs with external gears and a center sleeve with internal gears. The hubs are mounted on the shaft ends, and the center sleeve connects the two hubs. This design allows for angular and axial misalignment while transmitting torque between the shafts. Sleeve gear couplings are suitable for general-purpose applications and offer easy maintenance.
- Continuous Sleeve Gear Couplings: Continuous sleeve gear couplings are an improved version of sleeve gear couplings. In this design, the center sleeve is extended to cover the entire length of the hubs, providing additional support and increasing torque capacity. The continuous sleeve design reduces the bending effect on the shafts and allows for higher torque transmission.
- Flanged Sleeve Gear Couplings: Flanged sleeve gear couplings are similar to continuous sleeve couplings but include flanges at the ends of the center sleeve. These flanges provide extra support and help maintain proper alignment between the shafts. Flanged sleeve gear couplings are commonly used in high-speed and heavy-duty applications.
- Half Gear Couplings: Half gear couplings, also known as semi-rigid gear couplings, consist of one flexible half and one rigid half. The flexible half has internal gear teeth, while the rigid half has external gear teeth. This design allows for angular misalignment while offering higher torque capacity than fully flexible couplings. Half gear couplings are often used in applications where some degree of misalignment is expected, but not as much as what sleeve gear couplings can handle.
- Full Gear Couplings: Full gear couplings consist of two hubs with external gear teeth that mesh directly with each other. This design provides high torque capacity and is suitable for applications requiring minimal misalignment. Full gear couplings offer excellent torsional rigidity and are often used in precision applications where accurate shaft alignment is critical.
- Flexible Gear Couplings: Flexible gear couplings combine the features of gear couplings and flexible couplings. They consist of two hubs with external gears and a flexible element, such as a membrane or elastomeric material, connecting the hubs. This design allows for some misalignment while providing damping of vibrations and shock absorption.
Each type of gear coupling has its advantages and limitations, and the choice of coupling design depends on the specific requirements of the application, including the level of misalignment, torque capacity, speed, and environmental conditions.
editor by CX 2024-04-13
China wholesaler High Quality Machinery China Factory Transmission Drive Roller Chain Coupling Gear gear coupling
Product Description
Welcome to Visit our wuyi CHINAMFG chain factory in CHINA.
all kinds of chain couplings, including as belows:
4012-4014-4016 ,,6018,6571,8018,8571,1571,12571 and so on.
| Item | Sprocket / plate wheel/gear | |
| Standard | DIN, KANA, ANSI, ISO, etc | |
| Material | C45, stainless steel SS304 & SS316, Cast iron | |
| Bore | Pilot bore, finished bore, taper bore | |
| Surface Treatment | Black oxided, Zinc plated, Electrophoresis, self color and so on | |
| Heat treatment | Teeth inductive and quenching hardened HRC45-50,High frequency quenching or no hardened | |
| Process | Forging, Cutting, Hobbing teeth, CNC Lathe machining | |
|
|
||
| European Type | 03B, 04B, 05B, 06B, 081B, 083B/084B, 085B, 086B, 08B, 10B, 12B, 16B, 20B, 24B, 28B, 32B,40B,48B with simplex, duplex and triplex | |
| American Type | 25, 35, 40, 50, 60, 80, 100, 120, 140, 160, 200, 240 with simplex or duplex and triplex | |
|
Double pitch sprockets Type |
C2042, C2052, C2062, C2082, C2040, C2050, C2060, C2080 | |
| sprocket Type | Taper bore sprockets,Finished bore sprockets,Idler sprockets with ball bearing,Double simplex sprockets,Sprockets with split taper bushings,Sprockets with QD bushings,Double sprockets for 2 single chains,Type A & Type B, Single, Double, Triple -all kind sof standardf sprocket or wheel plate,and also can match with special conveyor chain, agricultural chain. or can make , according to customer reuqiryment | |
| Business type | Manufacturer/FACTORY | |
| Main export market | Europe, South America, Southeast Asia, Middle East, Africa | |
| Manufacturing method | Forged and then machined and hobbed | |
Bitmap
|
Plywood Case/Pallet/cartons or according to customer reuqiryment |
| we are CHINAMFG chain factory from CHINA. |
| We make roller chains over 20 years. main ASA chains: — main DIN chains:06b-08b-10b-12b-16b-20b-24b-32b main motorcycle chains: H 520 520H 530 Our quality: middle level and good and stable. Follow up XIHU (WEST LAKE) DIS.HUA standard We also exported many industrial sprockets together with our chains. We mainly exported chains to South America AND Europe. |
/* January 22, 2571 19:08:37 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
Materials Used in Manufacturing Gear Couplings
Gear couplings are designed to transmit torque between shafts while accommodating misalignment. To ensure the durability and reliability of gear couplings, manufacturers use a variety of materials, each with its specific properties. Commonly used materials in manufacturing gear couplings include:
- Steel: Steel is the most widely used material for gear couplings. It offers excellent strength, durability, and resistance to wear and fatigue. Steel gear couplings are suitable for a wide range of applications, including heavy-duty industrial machinery.
- Stainless Steel: Stainless steel is chosen for gear couplings that require resistance to corrosion and high-temperature environments. Stainless steel couplings are commonly used in food processing, pharmaceutical, and chemical industries.
- Alloy Steel: Alloy steel is utilized to enhance specific properties, such as increased strength and improved performance under high loads and extreme conditions. Alloy steel gear couplings are ideal for demanding applications in heavy industries.
- Cast Iron: Cast iron is known for its excellent machinability and good resistance to wear. Cast iron gear couplings are suitable for low to moderate torque applications and can be cost-effective in certain scenarios.
- Non-Metallic Materials: In some cases, non-metallic materials like nylon or urethane may be used for specific gear coupling applications, especially in situations where electrical isolation or chemical resistance is required.
The choice of material depends on the application’s demands, including the torque, speed, environmental conditions, and budget considerations. Gear coupling manufacturers carefully select materials that will provide optimal performance and longevity while meeting the specific requirements of the intended application.
editor by CX 2024-03-10
China Good quality Giicl Type Cast Steel Curved Tooth CNC Customizable Forged Steel Flexible Jaw Drive Shaft Pipe Connector Drum Gear Coupling gear coupling
Product Description
GIICL type Cast Steel Curved Tooth flexible drive shaft pipe connector Drum Gear Coupling
This shaft coupling is applicable to connecting 2 horizontal line shafting of coaxial line It has a drumshaped teeth shaft coupling with angular orientation compensation on relative deviation of 2 shafts.Temperature of the operating environment is:-20 ~ +80C.The nominal transmitting torque is0.4-4500KN*m.
Gear Couplings
Features:
Improve the starting capability of electric motor, protect motor against overloading, damp shock, load fluctuation and torsional vibration, and balance and load distribution in case of multimotor drives.
Applications:
Belt conveyers, csraper conveyers, and conveyers of all kinds Bucket elevators, ball mills, hoisters, crushers, excavators, mixers, straighteners, cranes, etc.
We can just upload very limited information about our couplings products here, for more info, please do not hesitate to wrtie to us for catalog and related technic info….
A coupling can interchange and replacement with lovejoy coupling is a device used to connect 2 shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join 2 pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
Our Company
Ever-power Group specialist in making all kinds of mechanical transmission and hydraulic transmission like: planetary gearboxes, worm reducers, in-line helical gear speed reducers, parallel shaft helical gear reducers, helical bevel reducers, helical worm gear reducers, agricultural gearboxes, tractor gearboxes, auto gearboxes, pto shafts, special reducer & related gear components and other related products, sprockets, hydraulic system, vacuum pumps, fluid coupling, gear racks, chains, timing pulleys, udl speed variators, v pulleys, hydraulic cylinder, gear pumps, screw air compressors, shaft collars low backlash worm reducers and so on. furthermore, we can produce customized variators, geared motors, electric motors and other hydraulic products according to customers’ drawings.
We provides a reliable grantee for the product’ s quality by advanced inspection and testing equipment. professional technical team, exquisite processing technology and strict control system.
In recent years, the company has been developing rapidly by its rich experience in production, advanced management system, standardized management system, strong technical force. We always adhere the concept of survival by quality, and development by innovation in science and technology.
Our Group is willing to work with you hand in hand and create brilliance together!
Material available
Low carbon steel, C45, 20CrMnTi, 42CrMo, 40Cr, stainless steel. Can be adapted regarding customer requirements.
Surface treatment
Blacking, galvanization, chroming, electrophoresis, color painting, …
Heat treatment
High frequency quenching heat treatment, hardened teeth, carbonizing, nitride, …
Certifications
FAQ:
Q: Are you trading company or manufacturer ?
A: Our group consists in 3 factories and 2 abroad sales corporations.
Q: Do you provide samples ? is it free or extra ?
A: Yes, we could offer the sample for free charge but do not pay the cost of freight.
Q: How long is your delivery time ? What is your terms of payment ?
A: Generally it is 40-45 days. The time may vary depending on the product and the level of customization. For standard products, the payment is: 30% T/T in advance ,balance before shippment.
Q: What is the exact MOQ or price for your product ?
A: As an OEM company, we can provide and adapt our products to a wide range of needs.Thus, MOQ and price may greatly vary with size, material and further specifications; For instance, costly products or standard products will usually have a lower MOQ. Please contact us with all relevant details to get the most accurate quotation.
If you have another question, please feel free to contact us.
Packing & Delivery
/* January 22, 2571 19:08:37 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
Types of Gear Coupling Designs
There are several types of gear coupling designs available, each with its own specific characteristics and applications. The main types of gear couplings are:
- Sleeve Gear Couplings: Sleeve gear couplings consist of two hubs with external gears and a center sleeve with internal gears. The hubs are mounted on the shaft ends, and the center sleeve connects the two hubs. This design allows for angular and axial misalignment while transmitting torque between the shafts. Sleeve gear couplings are suitable for general-purpose applications and offer easy maintenance.
- Continuous Sleeve Gear Couplings: Continuous sleeve gear couplings are an improved version of sleeve gear couplings. In this design, the center sleeve is extended to cover the entire length of the hubs, providing additional support and increasing torque capacity. The continuous sleeve design reduces the bending effect on the shafts and allows for higher torque transmission.
- Flanged Sleeve Gear Couplings: Flanged sleeve gear couplings are similar to continuous sleeve couplings but include flanges at the ends of the center sleeve. These flanges provide extra support and help maintain proper alignment between the shafts. Flanged sleeve gear couplings are commonly used in high-speed and heavy-duty applications.
- Half Gear Couplings: Half gear couplings, also known as semi-rigid gear couplings, consist of one flexible half and one rigid half. The flexible half has internal gear teeth, while the rigid half has external gear teeth. This design allows for angular misalignment while offering higher torque capacity than fully flexible couplings. Half gear couplings are often used in applications where some degree of misalignment is expected, but not as much as what sleeve gear couplings can handle.
- Full Gear Couplings: Full gear couplings consist of two hubs with external gear teeth that mesh directly with each other. This design provides high torque capacity and is suitable for applications requiring minimal misalignment. Full gear couplings offer excellent torsional rigidity and are often used in precision applications where accurate shaft alignment is critical.
- Flexible Gear Couplings: Flexible gear couplings combine the features of gear couplings and flexible couplings. They consist of two hubs with external gears and a flexible element, such as a membrane or elastomeric material, connecting the hubs. This design allows for some misalignment while providing damping of vibrations and shock absorption.
Each type of gear coupling has its advantages and limitations, and the choice of coupling design depends on the specific requirements of the application, including the level of misalignment, torque capacity, speed, and environmental conditions.
editor by CX 2024-03-09
China wholesaler High Quality Machinery China Factory Transmission Drive Roller Chain Coupling Gear gear coupling
Product Description
Welcome to Visit our wuyi CHINAMFG chain factory in CHINA.
all kinds of chain couplings, including as belows:
4012-4014-4016 ,,6018,6571,8018,8571,1571,12571 and so on.
| Item | Sprocket / plate wheel/gear | |
| Standard | DIN, KANA, ANSI, ISO, etc | |
| Material | C45, stainless steel SS304 & SS316, Cast iron | |
| Bore | Pilot bore, finished bore, taper bore | |
| Surface Treatment | Black oxided, Zinc plated, Electrophoresis, self color and so on | |
| Heat treatment | Teeth inductive and quenching hardened HRC45-50,High frequency quenching or no hardened | |
| Process | Forging, Cutting, Hobbing teeth, CNC Lathe machining | |
|
|
||
| European Type | 03B, 04B, 05B, 06B, 081B, 083B/084B, 085B, 086B, 08B, 10B, 12B, 16B, 20B, 24B, 28B, 32B,40B,48B with simplex, duplex and triplex | |
| American Type | 25, 35, 40, 50, 60, 80, 100, 120, 140, 160, 200, 240 with simplex or duplex and triplex | |
|
Double pitch sprockets Type |
C2042, C2052, C2062, C2082, C2040, C2050, C2060, C2080 | |
| sprocket Type | Taper bore sprockets,Finished bore sprockets,Idler sprockets with ball bearing,Double simplex sprockets,Sprockets with split taper bushings,Sprockets with QD bushings,Double sprockets for 2 single chains,Type A & Type B, Single, Double, Triple -all kind sof standardf sprocket or wheel plate,and also can match with special conveyor chain, agricultural chain. or can make , according to customer reuqiryment | |
| Business type | Manufacturer/FACTORY | |
| Main export market | Europe, South America, Southeast Asia, Middle East, Africa | |
| Manufacturing method | Forged and then machined and hobbed | |
Bitmap
|
Plywood Case/Pallet/cartons or according to customer reuqiryment |
| we are CHINAMFG chain factory from CHINA. |
| We make roller chains over 20 years. main ASA chains: — main DIN chains:06b-08b-10b-12b-16b-20b-24b-32b main motorcycle chains: H 520 520H 530 Our quality: middle level and good and stable. Follow up XIHU (WEST LAKE) DIS.HUA standard We also exported many industrial sprockets together with our chains. We mainly exported chains to South America AND Europe. |
/* March 10, 2571 17:59:20 */!function(){function s(e,r){var a,o={};try{e&&e.split(“,”).forEach(function(e,t){e&&(a=e.match(/(.*?):(.*)$/))&&1
How Does a Gear Coupling Protect Connected Equipment from Shock Loads and Vibrations?
Gear couplings are designed to provide excellent protection to connected equipment from shock loads and vibrations, making them ideal for use in demanding and heavy-duty applications. The design and features of gear couplings that contribute to this protection include:
- Flexible and Rigid Elements: Gear couplings consist of two hubs with external gears that mesh together. Between these two hubs, there is a center sleeve with internal gear teeth. The center sleeve acts as a flexible element, while the outer hubs act as rigid elements. This combination allows the gear coupling to transmit torque while absorbing and dampening shock loads and vibrations.
- Misalignment Compensation: Gear couplings can accommodate angular, parallel, and axial misalignment between shafts. When the connected equipment experiences misalignment due to dynamic forces or shock loads, the gear coupling can flex and adjust to these changes, preventing excessive stress on the shafts and equipment.
- High Torsional Stiffness: Gear couplings offer high torsional stiffness, meaning they have minimal angular deflection under load. This stiffness helps maintain precise alignment and reduces the likelihood of damage to the connected equipment caused by misalignment-induced vibrations.
- Load Distribution: The toothed gear design of gear couplings ensures a large surface area of contact between the gears. This spreads the torque evenly across the gear teeth, resulting in a uniform distribution of load and reducing the concentration of stress on specific areas.
- Damping Characteristics: The flexible center sleeve in the gear coupling acts as a damping element that absorbs and dissipates vibrations, further protecting the connected equipment from harmful oscillations.
- High-Speed Balancing: Gear couplings are precisely balanced during manufacturing to minimize vibrations and ensure smooth operation even at high speeds. Proper balancing helps prevent resonances and reduces the impact of shock loads on the connected equipment.
By effectively absorbing and dampening shock loads and vibrations, gear couplings extend the life of the connected equipment and surrounding components, reduce maintenance requirements, and contribute to a more reliable and efficient mechanical system. However, it is essential to select the appropriate size and type of gear coupling based on the specific application and operating conditions to ensure optimal protection and performance.
editor by CX 2024-02-08
China Custom Flange Cast Iron Coupling Steel Universal Joint Cardan Pump Rubber Motor Disc Curved Tooth Flex Rigid Drive Shaft Nm Yox Fluid Jaw Flexible Chain Gear Couplings gear coupling
Product Description
Flange Cast Iron Coupling Steel Universal Joint Cardan Pump Rubber Motor Disc CHINAMFG Flex Rigid Drive Shaft NM yox Fluid Jaw Flexible Chain Gear Couplings
Manufacturer of Couplings, Fluid Coupling, JAW Coupling, can interchange and replacement of lovejoy coupling and so on.
A coupling can interchange and replacement of lovejoy coupling is a device used to connect 2 shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join 2 pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
Coupling is a jaw type coupling that works for a variety of light duty to heavy duty motors used in electric power transmission.
This is 1 of our safest types of products. The reason being that these couplings work even when the elastomer fails and there is no metal to metal contact.
They perform in well-standing oil, grease, moisture, sand, and dirt and nearly 850,000 bore combinations that can be customised as per the customer’s needs.
They are used in light-weight, medium, or heavy electrical motors and devices for power transmission through internal combustion.
Production workshop:
Company information:
Materials Used in Manufacturing Gear Couplings
Gear couplings are designed to transmit torque between shafts while accommodating misalignment. To ensure the durability and reliability of gear couplings, manufacturers use a variety of materials, each with its specific properties. Commonly used materials in manufacturing gear couplings include:
- Steel: Steel is the most widely used material for gear couplings. It offers excellent strength, durability, and resistance to wear and fatigue. Steel gear couplings are suitable for a wide range of applications, including heavy-duty industrial machinery.
- Stainless Steel: Stainless steel is chosen for gear couplings that require resistance to corrosion and high-temperature environments. Stainless steel couplings are commonly used in food processing, pharmaceutical, and chemical industries.
- Alloy Steel: Alloy steel is utilized to enhance specific properties, such as increased strength and improved performance under high loads and extreme conditions. Alloy steel gear couplings are ideal for demanding applications in heavy industries.
- Cast Iron: Cast iron is known for its excellent machinability and good resistance to wear. Cast iron gear couplings are suitable for low to moderate torque applications and can be cost-effective in certain scenarios.
- Non-Metallic Materials: In some cases, non-metallic materials like nylon or urethane may be used for specific gear coupling applications, especially in situations where electrical isolation or chemical resistance is required.
The choice of material depends on the application’s demands, including the torque, speed, environmental conditions, and budget considerations. Gear coupling manufacturers carefully select materials that will provide optimal performance and longevity while meeting the specific requirements of the intended application.
editor by CX 2023-11-16
China supplier American Type Worm Gear Drive W1 W2 Flexible Exhaust Pipe Couplings gear coupling
Product Description
Product Name
American Type Hose Clamp
Product Parameters
| Item(Small American Type) | Model | Brand width(mm) | Thickness(mm) | PCS/Bag | PCS/BOX |
| CZX-CLA-001 | 6-12mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-002 | 10-16mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-003 | 13-19mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-004 | 16-25mm | 8 | 0.6 | 100 | 5000 |
| CZX-CLA-005 | 19-29mm | 8 | 0.6 | 100 | 5000 |
| Item(large American Type) | Model | Brand width(mm) | Thickness(mm) | KG/100PCS | PCS/BOX |
| CZX-CLA-001 | 14-27 | 12 | 0.6 | 1 | 2000 |
| CZX-CLA-002 | 18-32 | 12 | 0.6 | 1.3 | 2000 |
| CZX-CLA-003 | 21-38 | 12 | 0.6 | 1.55 | 2000 |
| CZX-CLA-004 | 21-44 | 12 | 0.6 | 1.61 | 2000 |
| CZX-CLA-005 | 27-51 | 12 | 0.6 | 1.7 | 2000 |
| CZX-CLA-006 | 33-57 | 12 | 0.6 | 1.8 | 2000 |
| CZX-CLA-007 | 40-63 | 12 | 0.6 | 1.9 | 1500 |
| CZX-CLA-008 | 46-70 | 12 | 0.6 | 2 | 1200 |
| CZX-CLA-009 | 52-76 | 12 | 0.6 | 2.2 | 1000 |
| CZX-CLA-571 | 59-82 | 12 | 0.6 | 2.36 | 1000 |
| CZX-CLA-011 | 65-89 | 12 | 0.6 | 2.5 | 800 |
| CZX-CLA-012 | 72-95 | 12 | 0.6 | 2.6 | 800 |
| CZX-CLA-013 | 78-101 | 12 | 0.6 | 2.7 | 700 |
| CZX-CLA-014 | 84-108 | 12 | 0.6 | 2.75 | 600 |
| CZX-CLA-015 | 91-114 | 12 | 0.6 | 2.8 | 600 |
| CZX-CLA-016 | 105-127 | 12 | 0.6 | 3 | 600 |
| CZX-CLA-017 | 118-140 | 12 | 0.6 | 3.4 | 500 |
| CZX-CLA-018 | 130-152 | 12 | 0.6 | 3.5 | 500 |
| CZX-CLA-019 | 141-165 | 12 | 0.6 | 3.7 | 500 |
| CZX-CLA-571 | 155-178 | 12 | 0.6 | 4 | 500 |
| CZX-CLA-571 | 175-197 | 12 | 0.6 | 4.3 | 400 |
| CZX-CLA-571 | 194-216 | 12 | 0.6 | 4.4 | 400 |
| CZX-CLA-571 | 213-235 | 12 | 0.6 | 4.9 | 400 |
| CZX-CLA-571 | 232-254 | 12 | 0.6 | 5.3 | 400 |
| CZX-CLA-571 | 251-273 | 12 | 0.6 | 5.6 | 400 |
| CZX-CLA-026 | 270-292 | 12 | 0.6 | 6 | 400 |
| CZX-CLA-571 | 289-311 | 12 | 0.6 | 6.2 | 400 |
| CZX-CLA-571 | 100 | 12 | 0.6 | ||
| CZX-CLA-571 | 200 | 12 | 0.6 | ||
| CZX-CLA-030 | 300 | 12 | 0.6 | ||
| CZX-CLA-031 | 350 | 12 | 0.6 | ||
| CZX-CLA-032 | 400 | 12 | 0.6 | ||
| CZX-CLA-033 | 450 | 12 | 0.6 | ||
| CZX-CLA-034 | 500 | 12 | 0.6 | ||
| CZX-CLA-035 | 550 | 12 | 0.6 | ||
| CZX-CLA-036 | 600 | 12 | 0.6 |
| Product name | stainless steel clamp(201,304,316 is optional) |
| Features | Exquisite workmanship, no rust |
| Product properties | see parameter table |
| Product color | Stainless steel color |
| Product material | Authentic stainless steel all steel (including screws) |
| Product Specifications | Various specifications (various sizes can be customized) |
| Product Usage | Widely used in stainless steel, wire and cable, new energy vehicles, hoses, ships, chemicals and other industries |
| The hose clamp is relatively small and its value is relatively low, but the role of the hose clamp is huge. American hose clamp, also known as clamp. American stainless steel hose clamps: divided into small American hose clamps and large American hose clamps. The width of the hose clamps is 12.7mm and 14.2mm respectively. Using through-hole technology, the hose clamp has a wide range of applications. It is suitable for fasteners for connecting soft and hard pipes with a thickness of 30mm or more. The appearance after assembly is beautiful. Features: The worm has low friction, which is suitable for middle and high-end vehicles, pole-holding equipment or the connection of anti-corrosion materials. | |
| American type hose clamp: divided into 2 types: iron galvanized and stainless steel. The main difference is that the button pitch is perforated (ie through-hole button). The market is mainly made of stainless steel, which is mainly used in high-end markets such as auto parts and poles. The price Higher than the other two. | |
Detailed Photos
Product Application
Production Workshop
International Experiance
Certifications
After Sales Service
1.Reply in 24 hours.
2.In time response and professional suggestions.
3.Replacement product and tailor-made product both can do.
4.Small trial order accepted.
5.Certification, complete certificates,like CE, EU,Rohs, FDA.
6.Good quality and competitive price.
Contact Person
Celina Du
HangZhou Xihu (West Lake) Dis. Rubber & Plastic New Material Co., Ltd
How Does a Gear Coupling Handle Angular, Parallel, and Axial Misalignment?
Gear couplings are designed to handle various types of misalignment, including angular, parallel, and axial misalignment. Here’s how they handle each type:
- Angular Misalignment: Angular misalignment occurs when the two connected shafts are not collinear and form an angle with each other. Gear couplings can accommodate angular misalignment due to the flexibility of their gear teeth. The gear teeth allow a slight angular movement between the shafts without causing significant stress on the coupling.
- Parallel Misalignment: Parallel misalignment occurs when the two connected shafts are offset along their axis but remain parallel to each other. Gear couplings can handle parallel misalignment to some extent due to the slight axial movement allowed by the gear teeth. However, for larger parallel misalignments, special gear couplings with spacer elements or other features may be required.
- Axial Misalignment: Axial misalignment occurs when the two connected shafts are not in the same axial plane and have an offset along their length. Gear couplings can handle a certain degree of axial misalignment because the gear teeth can accommodate small axial movements without causing damage to the coupling or connected equipment.
The ability of gear couplings to handle misalignment is one of their key advantages over other types of couplings. The gear teeth act as flexible elements that can compensate for minor misalignments, reducing the stress and wear on the coupling and the connected equipment. However, it is essential to ensure that the misalignment remains within the allowable limits specified by the coupling manufacturer to maintain optimal performance and reliability.
editor by CX 2023-11-16
China supplier Giicl Type Cast Steel Curved Tooth CNC Customizable Forged Steel Flexible Jaw Drive Shaft Pipe Connector Drum Gear Coupling gear coupling
Product Description
GIICL type Cast Steel Curved Tooth flexible drive shaft pipe connector Drum Gear Coupling
This shaft coupling is applicable to connecting 2 horizontal line shafting of coaxial line It has a drumshaped teeth shaft coupling with angular orientation compensation on relative deviation of 2 shafts.Temperature of the operating environment is:-20 ~ +80C.The nominal transmitting torque is0.4-4500KN*m.
Gear Couplings
Features:
Improve the starting capability of electric motor, protect motor against overloading, damp shock, load fluctuation and torsional vibration, and balance and load distribution in case of multimotor drives.
Applications:
Belt conveyers, csraper conveyers, and conveyers of all kinds Bucket elevators, ball mills, hoisters, crushers, excavators, mixers, straighteners, cranes, etc.
We can just upload very limited information about our couplings products here, for more info, please do not hesitate to wrtie to us for catalog and related technic info….
A coupling can interchange and replacement with lovejoy coupling is a device used to connect 2 shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join 2 pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
Our Company
Ever-power Group specialist in making all kinds of mechanical transmission and hydraulic transmission like: planetary gearboxes, worm reducers, in-line helical gear speed reducers, parallel shaft helical gear reducers, helical bevel reducers, helical worm gear reducers, agricultural gearboxes, tractor gearboxes, auto gearboxes, pto shafts, special reducer & related gear components and other related products, sprockets, hydraulic system, vacuum pumps, fluid coupling, gear racks, chains, timing pulleys, udl speed variators, v pulleys, hydraulic cylinder, gear pumps, screw air compressors, shaft collars low backlash worm reducers and so on. furthermore, we can produce customized variators, geared motors, electric motors and other hydraulic products according to customers’ drawings.
We provides a reliable grantee for the product’ s quality by advanced inspection and testing equipment. professional technical team, exquisite processing technology and strict control system.
In recent years, the company has been developing rapidly by its rich experience in production, advanced management system, standardized management system, strong technical force. We always adhere the concept of survival by quality, and development by innovation in science and technology.
Our Group is willing to work with you hand in hand and create brilliance together!
Material available
Low carbon steel, C45, 20CrMnTi, 42CrMo, 40Cr, stainless steel. Can be adapted regarding customer requirements.
Surface treatment
Blacking, galvanization, chroming, electrophoresis, color painting, …
Heat treatment
High frequency quenching heat treatment, hardened teeth, carbonizing, nitride, …
Certifications
FAQ:
Q: Are you trading company or manufacturer ?
A: Our group consists in 3 factories and 2 abroad sales corporations.
Q: Do you provide samples ? is it free or extra ?
A: Yes, we could offer the sample for free charge but do not pay the cost of freight.
Q: How long is your delivery time ? What is your terms of payment ?
A: Generally it is 40-45 days. The time may vary depending on the product and the level of customization. For standard products, the payment is: 30% T/T in advance ,balance before shippment.
Q: What is the exact MOQ or price for your product ?
A: As an OEM company, we can provide and adapt our products to a wide range of needs.Thus, MOQ and price may greatly vary with size, material and further specifications; For instance, costly products or standard products will usually have a lower MOQ. Please contact us with all relevant details to get the most accurate quotation.
If you have another question, please feel free to contact us.
Packing & Delivery
Selection of Gear Couplings for Specific Applications
Choosing the appropriate gear coupling for a specific application involves considering several factors to ensure optimal performance and reliability. Here are the key steps in the selection process:
- Identify Application Requirements: Understand the specific requirements of the application, including the torque and speed requirements, operating conditions, and the amount of angular and axial misalignment expected in the system.
- Calculate Torque and Speed: Determine the required torque and speed ratings for the gear coupling based on the power transmission needs of the application. Consider both peak and continuous torque requirements.
- Consider Misalignment: Evaluate the amount and type of misalignment that the gear coupling needs to accommodate. Different gear coupling designs have varying degrees of misalignment capabilities, so it’s essential to choose one that can handle the expected misalignment in the system.
- Check Space Constraints: Consider the available space for installing the gear coupling. Some applications may have limited space, requiring compact or specially designed couplings to fit properly.
- Assess Environmental Conditions: Determine if the application involves exposure to extreme temperatures, corrosive substances, or other harsh environmental factors. Select a gear coupling made from materials that can withstand the specific environmental conditions.
- Consider Maintenance Requirements: Evaluate the maintenance needs of the gear coupling. Some designs may require more frequent maintenance than others. For applications where regular maintenance is challenging, consider maintenance-free gear coupling options.
- Check Industry Standards and Certifications: Ensure that the selected gear coupling meets relevant industry standards and certifications to guarantee quality and safety.
- Consult with Experts: If needed, seek guidance from coupling manufacturers or engineering experts who can provide valuable insights and recommendations based on their experience and expertise.
By carefully considering these factors and understanding the specific demands of the application, you can select the most suitable gear coupling that will provide reliable and efficient power transmission while minimizing the risk of premature failure or downtime.
editor by CX 2023-10-08
China Standard Flange Cast Iron Coupling Steel Universal Joint Cardan Pump Rubber Motor Disc Curved Tooth Flex Rigid Drive Shaft Nm Yox Fluid Jaw Flexible Chain Gear Couplings gear coupling
Product Description
Flange Cast Iron Coupling Steel Universal Joint Cardan Pump Rubber Motor Disc CHINAMFG Flex Rigid Drive Shaft NM yox Fluid Jaw Flexible Chain Gear Couplings
Manufacturer of Couplings, Fluid Coupling, JAW Coupling, can interchange and replacement of lovejoy coupling and so on.
A coupling can interchange and replacement of lovejoy coupling is a device used to connect 2 shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join 2 pieces of rotating equipment while permitting some degree of misalignment or end movement or both. In a more general context, a coupling can also be a mechanical device that serves to connect the ends of adjacent parts or objects. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.
Coupling is a jaw type coupling that works for a variety of light duty to heavy duty motors used in electric power transmission.
This is 1 of our safest types of products. The reason being that these couplings work even when the elastomer fails and there is no metal to metal contact.
They perform in well-standing oil, grease, moisture, sand, and dirt and nearly 850,000 bore combinations that can be customised as per the customer’s needs.
They are used in light-weight, medium, or heavy electrical motors and devices for power transmission through internal combustion.
Production workshop:
Company information:
Can Gear Couplings Be Used in Both Horizontal and Vertical Shaft Arrangements?
Yes, gear couplings are versatile and can be used in both horizontal and vertical shaft arrangements.
Horizontal Shaft Arrangements: In horizontal shaft configurations, gear couplings are commonly employed to connect two shafts in-line with each other. The gear coupling’s flexible design accommodates for slight misalignment and torsional movement between the shafts, making it suitable for various industrial applications. These couplings can handle high torque loads and are often used in heavy-duty machinery such as steel rolling mills, mining equipment, and conveyors.
Vertical Shaft Arrangements: Gear couplings are also well-suited for vertical shaft arrangements, where the connected shafts are oriented one above the other. In such cases, gravity can cause additional axial loads on the coupling, which gear couplings are designed to handle. The gear coupling’s capacity to accommodate both angular and axial misalignment is essential in vertical applications, where thermal expansion and contraction may induce relative movement between the shafts.
Whether in horizontal or vertical shaft configurations, gear couplings provide reliable power transmission and are widely used in various industrial settings. However, it is essential to ensure proper alignment and maintenance for optimal performance and to prevent premature wear or failure of the coupling.
editor by CX 2023-09-21