The driveline—driveshaft, universal joints, and support bearings — transfers power from the transmission to the axles. It twists under heavy loads, flexes over rough ground, and spins at high speed. When it fails, the loader stops. Here are four checks that keep your driveline intact.

1. Grease Universal Joints Weekly

U-joints have needle bearings that need fresh grease to survive. Most have a grease fitting on each cross. Pump grease until you see clean grease purging from all four seal areas. If one bearing does not purge, the grease channel is blocked — clear it or replace the joint. Use a lithium-complex EP grease. Dry U-joints wear quickly, develop play, and eventually break, dropping the driveshaft.

2. Check for Driveline Play

With the engine off and the parking brake set, grasp the driveshaft near each U-joint and try to rotate it by hand. There should be no rotational play. Any movement indicates worn needle bearings or trunnions. Also push the shaft up and down — movement at the joint means bearing wear. For splined slip joints, check for axial play by pushing and pulling the shaft. Excessive play means splines are worn. Replace worn U-joints or slip joints before they fail completely.

3. Inspect the Center Support Bearing

Loaders with two-piece driveshafts have a center bearing mounted to the frame. A worn center bearing causes vibration and can allow the shaft to wobble. Check the rubber isolator for cracks or separation. Push the shaft up and down — the bearing should have minimal movement. If the bearing is loose or the rubber is deteriorated, replace it. A failed center bearing can let the driveshaft drop, damaging brake and fuel lines.

4. Look for Balance Weights and Shaft Damage

The driveshaft is balanced at the factory. Small balance weights are welded to the tube. If these are missing or the shaft has impact damage, vibration will occur. Inspect the tube for dents or dings. A bent shaft cannot be straightened — replace it. Also check the weld yokes for cracks, especially where the tube meets the yoke. A cracked yoke will fail suddenly.

Quick field check: With the engine off and the loader parked on level ground, crawl under the machine and shake the driveshaft in all directions. Excessive looseness or clunking indicates worn components that need immediate attention. A tight driveline is a reliable driveline.

Want a driveline inspection checklist for your loader? Reply with your loader model — we will send a PDF with grease points, torque specifications, and bearing replacement intervals.