NM Couplings
NM couplings are available in the widest range of stock bore/keyway combinations in the industry. These couplings do not require lubrication and offer highly dependable performance for light, medium, and heavy-duty electrical motor and internal combustion power transmission applications. NM couplings are ideal for powering industrial equipment including pumps, gearboxes, compressors, blowers, mixers, and conveyors. Choose AGKNX’s couplings to deliver reliable and efficient power transmission solutions for your industrial applications.
NM couplings are available in the widest range of stock bore/keyway combinations in the industry. These couplings do not require lubrication and offer highly dependable performance for light, medium, and heavy-duty electrical motor and internal combustion power transmission applications. NM couplings are ideal for powering industrial equipment including pumps, gearboxes, compressors, blowers, mixers, and conveyors. Choose AGKNX's couplings to deliver reliable and efficient power transmission solutions for your industrial applications.
NM Coupling Size Chart
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| NM Coupling Size | Rated Torque | Max Speed (RPM.) | Bore, D | Dimension(mm.) | Total Weight (kg.) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Normal (Nm.) | Max (Nm.) | Min. (mm.) | Max. (mm.) | A | B | LTB | L | S | C | E | F | Number Of jaws | |||
| NM50 | 13 | 27 | 13,500 | 7 | 19 | 50 | 33 | 25 | 52.0 | 2.0 ±0.5 | 49 | 44.5 | 31.5 | 4 | 0.48 |
| NM67 | 22 | 45 | 10,000 | 9 | 28 | 67 | 46 | 30 | 62.5 | 2.5 ±0.5 | 66 | 59.0 | 41.5 | 4 | 1.02 |
| NM82 | 48 | 100 | 8,000 | 10 | 32 | 82 | 53 | 40 | 83.0 | 3.0 ±1.0 | 81 | 73.5 | 50.5 | 4 | 1.88 |
| NM97 | 96 | 200 | 7,000 | 12 | 42 | 97 | 69 | 50 | 103.0 | 3.0 ±1.0 | 96 | 91.0 | 65.0 | 5 | 3.54 |
| NM112 | 150 | 310 | 6,000 | 14 | 48 | 112 | 79 | 60 | 123.5 | 3.5 ±1.0 | 111 | 104.0 | 75.5 | 6 | 5.40 |
| NM128 | 250 | 500 | 5,000 | 18 | 55 | 128 | 90 | 70 | 143.5 | 3.5 ±1.0 | 127 | 116.5 | 85.0 | 6 | 8.10 |
| NM148 | 390 | 800 | 4,500 | 22 | 65 | 148 | 107 | 80 | 163.5 | 3.5 ±1.0 | 147 | 135.0 | 105.5 | 7 | 13.50 |
| NM168 | 630 | 1,300 | 4,000 | 28 | 75 | 168 | 124 | 90 | 183.5 | 3.5 ±1.5 | 167 | 154.0 | 121.0 | 8 | 19.30 |
Key Features of NM Couplings
NM couplings are a type of flexible coupling commonly used in mechanical power transmission systems to connect two shafts, typically between a motor and a driven component like a pump or gearbox. Here are the key features of NM couplings based on their typical design and application:
- Flexible Design with Elastomeric Element: NM couplings consist of two metal hubs (usually made of high-grade cast iron) and a flexible ring or sleeve, often made of nitrile rubber (NBR). This elastomeric element allows the coupling to absorb misalignment, vibrations, and shocks, providing flexibility while transmitting torque.
- Misalignment Compensation: They can accommodate various types of shaft misalignment, including angular, parallel (radial), and axial displacement. This makes them suitable for applications where perfect shaft alignment is difficult to maintain.
- Torsional Damping: The rubber element in NM couplings provides excellent damping properties, reducing torsional vibrations and protecting connected equipment from sudden torque changes or shock loads.
- High Torque Capacity: NM couplings are designed to handle a wide range of torque requirements, making them versatile for light, medium, and heavy-duty applications. Specific torque ratings depend on the size, with models available from small (e.g., 23 Nm) to large (e.g., over 2942 Nm) capacities.
- Durability and Resistance: The nitrile rubber used in the flexible ring is resistant to oil, grease, dirt, moisture, and certain chemicals, while also operating effectively in a temperature range of approximately -40°C to +100°C. The cast iron hubs add strength and durability, especially under fluctuating loads.
- No Lubrication Required: Unlike some other coupling types (e.g., gear couplings), NM couplings are maintenance-free due to their dry-running design, which eliminates the need for lubrication and reduces operational costs.
- Low Noise Operation: The damping effect of the rubber sleeve contributes to quieter performance, which is beneficial in noise-sensitive environments.
- Wide Application Range: NM couplings are widely used in industrial equipment such as pumps, compressors, conveyors, blowers, and mixers, thanks to their versatility and reliability in general machinery.
Common Applications of NM Couplings
NM couplings, often referred to as nylon sleeve couplings or gear couplings with nylon sleeves, are flexible mechanical devices used to connect two shafts for transmitting power while accommodating misalignment and reducing vibration. Here are some common applications:
- Pumps and Motors: NM couplings are widely used in pump systems (e.g., water pumps, hydraulic pumps) and electric motor setups. Their ability to handle slight misalignments and dampen vibrations makes them ideal for ensuring smooth operation in these systems.
- Industrial Machinery: They are employed in various industrial machines like conveyors, compressors, and blowers. The flexibility and durability of the nylon sleeve help protect equipment from shock loads and wear.
- HVAC Systems: In heating, ventilation, and air conditioning equipment, NM couplings connect motors to fans or blowers, providing reliable torque transmission while minimizing noise and vibration.
- Agricultural Equipment: These couplings are used in machinery such as tractors, tillers, and harvesters, where they handle rugged conditions and misalignment between drivelines.
- Small Power Tools: In tools like drills, grinders, or saws, NM couplings can be found connecting the motor to the working component, offering a balance of flexibility and strength.
- Automotive Applications: Though less common, they can be used in auxiliary systems like power steering pumps or alternator drives, where compact and efficient power transmission is needed.
NM Coupling Installation Steps
1. Clean Shafts and Coupling Surfaces: Prepare the shafts by cleaning them with a degreaser or solvent to remove dirt, grease, rust, or debris. Similarly, clean the inner bores of the coupling hubs to ensure a secure fit. Proper cleaning prevents slippage and ensures a tight connection between the shafts and hubs during operation.
2. Verify Shaft and Bore Compatibility: Measure the shaft diameters and the coupling hub bores using precision tools like calipers or micrometers. Confirm that the bore sizes match the shafts, accounting for keyways if present. This step ensures proper fitment and prevents issues like excessive vibration or hub damage during installation.
3. Install the First Hub on the Driving Shaft: Slide the first coupling hub onto the driving shaft (e.g., motor shaft). Align it properly, ensuring it sits flush against any shoulder or keyway. If a key is used, insert it snugly into the keyway. Secure the hub by tightening the set screws or clamping bolts to the manufacturer’s recommended torque.
4. Position the Rubber Spider: Place the rubber spider (flexible element) into the grooves or jaws of the installed hub. Ensure it is seated evenly and fully engaged with the hub’s teeth or slots. The spider’s flexibility allows it to absorb misalignment and vibrations, so correct placement is critical for effective torque transmission.
5. Align the Second Shaft: Bring the driven shaft (e.g., pump shaft) into position, aligning it with the first shaft as closely as possible. Use a straight edge or dial indicator to check for angular and parallel misalignment. Adjust the shaft positions using shims or leveling tools to minimize misalignment within the coupling’s tolerance limits.
6. Install the Second Hub on the Driven Shaft: Slide the second hub onto the driven shaft, ensuring it engages with the rubber spider already positioned in the first hub. Align the hub so the spider fits securely into its grooves or jaws. Tighten the set screws or clamping bolts to the specified torque, maintaining even pressure.
7. Check Alignment and Clearance: After both hubs are installed, recheck the alignment between the shafts using a dial indicator or laser alignment tool. Ensure the gap between the hubs allows the rubber spider to flex without excessive compression or stretching. Adjust as needed to maintain proper axial clearance per the manufacturer’s specifications.
8. Tighten All Fasteners Securely: Using a torque wrench, tighten all set screws or clamping bolts on both hubs to the manufacturer’s recommended torque values. Tighten in a cross pattern if multiple fasteners are present to ensure even pressure. This step prevents loosening during operation and ensures a firm connection.
9. Perform a Test Run and Final Inspection: Power on the machinery briefly to test the coupling under load. Listen for unusual noises and check for excessive vibration, which could indicate misalignment or improper installation. Stop the system and re-inspect all components, making adjustments if necessary to ensure smooth operation.
Additional information
| Edited by | Yjx |
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