Frequently Asked Questions for Ball-cage Constant Velocity Universal Coupling

1. Q: Why is the Ball-cage CV coupling called a constant velocity universal coupling?
A: The cage keeps the balls on the bisecting plane of the shaft angle. The driving and driven shafts share the same instantaneous angular velocity, without the periodic speed fluctuation of cross-spider universal joints, realizing smooth constant-velocity transmission.

2. Q: How to choose between fixed type and plunging type Ball-cage CV couplings?
A: The fixed type only compensates for angular misalignment. The plunging type has longer raceways. Besides angular compensation, it can also accommodate axial displacement, ideal for working conditions with thermal expansion and axial float of equipment.

3. Q: What is the maximum allowable operating angle of the Ball-cage CV coupling?
A: A standard single-joint fixed type allows 35°～42°, while the plunging type has a slightly smaller angle. Long-term operation at the extreme angle is not recommended. Refer to catalogue data.

4. Q: How to select between Ball-cage CV coupling and cross-spider universal joints?
A: Choose Ball-cage CV coupling for smooth transmission, low vibration, low noise and high-speed applications. Select cross-spider universal joints if uniform speed is not critical and cost control is prioritized.

5. Q: What safety factor should be adopted for selection?
A: 1.2～1.5 for steady operation; ≥2.0 is recommended for heavy-load conditions with frequent start-stop and shocks.

6. Q: Is alignment still required even with misalignment compensation?
A: The compensation is designed to absorb reasonable deviations rather than large misalignment errors. Additional bending moment will greatly shorten service life.

7. Q: What causes abnormal noise and vibration during operation?
A: Common causes include contaminants entering through damaged dust boot, dried or lost grease, over-angle / over-torque operation, excessive internal wear clearance or unbalance. Stop the machine for inspection promptly.

8. Q: Can it run forward and backward? Is it suitable for high speed?
A: Standard models support bi-directional rotation. Inform us of the operating speed for high-speed applications so that dynamic balancing of Grade G2.5/G6.3 can be arranged as required.

9. Q: Is it suitable for continuous heavy shock loads?
A: Not recommended. The balls make point contact with raceways. Continuous heavy shocks easily lead to raceway pitting and ball spalling.

10. Q: Which component fails most easily on a Ball-cage CV coupling?
A: The dust boot. Once damaged, sand, mud and moisture ingress will rapidly cause abrasive wear on balls and raceways. This is the leading cause of early failure.

11. Q: Can ordinary lubricant be used?
A: No. Molybdenum disulfide extreme pressure grease is preferred. Apply a moderate amount; overfilling may lead to overheating.

12. Q: What is the maintenance interval?
A: Inspect and replenish grease every 3–6 months for clean indoor conditions. Shorten the interval to 1 month for dusty, outdoor or high-temperature environments, and check the seals at the same time.

13. Q: Can the coupling continue running if pitting appears on raceways?
A: Not recommended. Pitting is fatigue damage that propagates progressively, which may result in ball fracture and sudden equipment lock-up.