U Joint Repair & Maintenance

U-Joint Repair

All Power Transmission Inc. offers full machine shop capabilities for any necessary repairs or emergency U-Joint replacement requirements. Repairs of all brands of universal joints driveshafts can be accommodated. Each repair is disassembled and inspected in the following areas:

Slip spines are checked for backlash and run-out.
Flange mounting faces are checked for straightness and bolt holes are inspected for wear.
Universal joints are removed, visually inspected for damage, and measured to factory tolerances.
Welds are magnetic particle inspected upon request.
Shafts are reassembled with required parts, welded*, straightened, dynamically balanced, and painted to customer specifications.

*The welding processes used by All Power Transmission Inc. are completely certified.

Warning: Rotating driveshafts can be dangerous. Use shaft guards to help prevent serious injury to personnel.

U-Joint Maintenance

Among the most common causes of U-joint and slip failure is the lack of proper lubrication. Properly sized U-joints that are adequately lubricated at recommended intervals will normally meet or exceed operational requirements. Proper lubrication flushes of U-joints thus remove contaminants from the bearing caps.

U-Joint Lubrication

Proper cross and bearing lubrication requires purging the U-joint. The seals are designed to relieve contaminants and old lubricants when fresh grease is installed. This occurs when excess lubricant appears at the bearing caps seals. All bearing caps must be purged to insure full lubrication. To remedy a non-purged bearing cap, side to side movement of the shaft in all directions may loosen the seal. If the seal will not purge, the cap should be partially removed, then purged.

Slip Spline Lubrication

Proper slip spline lubrication will occur when the shaft is in its operating length. Lubricant should be installed at the center grease fitting until excess grease "purges" from beneath the seal tube.

Lubrication Specifications

Extreme pressure (EP) greases of high quality are recommended for universal joints and slip splines. Lithium soap base greases meeting National Lubricating Greases Institute Grade 1 (NGL1) and Grade 2 are preferred. Avoid using greases that tend to separate and cake. For applications with shaft speeds less than 500 rpm, a mineral oil SAE 140 to SAE 250 viscosity may be used.

Lubrication Intervals

U-joint lubrication must occur after the first 200 hours of service and three months thereafter. Severe applications require shorter intervals of lubrication service. The slip spline should be lubricated each time the U-joint is serviced.

Maintenance Inspections

Prior to proper lubrication a general shaft inspection should be done. All fasteners on the joints or mating flanges should be checked for tightness. U-joints and the slip spline should be checked for play, if any variance is noted the shaft should be overhauled and balanced. Any vibration or abnormal noise noticed during operation should be located and remedied at once.

Warning: Rotating driveshafts can be dangerous. Use shaft guards to help prevent serious injury to personnel.