Kubota KX057-4 Weak Side Travel Motor — Diagnostic Guide

Symptoms

• Machine drifts or pulls down in one direction during dual-joystick travel
• A lack of power to turn towards one track
• Low hydraulic pressure reading on one travel pilot line
• Excessive heat buildup around one travel motor assembly

Possible Causes

• Internal wear of travel motor pistons and rotary plate causing bypass
• Leaking swivel joint/center joint internal seals
• Worn spool section within the main control valve bank
• Pilot control oil pressure delivery is too low to fully stroke the spool

Diagnostic Procedure

1. 1
   Measure Travel Pilot Command Pressure

   Install a 1000 psi hydraulic pressure gauge to the travel spool pilot ports on the control block. Run the engine and stroke each travel lever fully to confirm they reach at least 500 psi pilot command pressure.
2. 2
   Perform Motor Case Drain Flow Test

   Disconnect the case drain line at the weak travel motor, plug the returning side hose, and route the motor out flow into a clean measuring bucket. Run travel in high idle for 1 minute; flow exceeding 4-5 liters/min indicates excessive internal wear.
3. 3
   Perform Swivel Joint Bypass Test

   Apply pressure to the system and verify temperature differences before and after the central swivel joint. Cross-connect travel hose bundles to isolate the swivel joint; if the drift direction swaps sides, the rotary seals are bypassing internally.
4. 4
   Test Travel Main Port Relief Valves

   Identify the high-pressure travel relief valves. Swap the forward relief valve with the reverse relief valve on the weak side. If the travel weakness transfers to the opposite travel direction, replace the relief spool.

Common Repairs

• Rebuilding or replacing the weak hydraulic travel motor assembly
• Replacing the seal kit pack inside the machine's center swivel joint
• Shimming or replacing the dual travel port relief valves

Safety Precautions

• Always elevate the machine track carefully off the ground using the boom/bucket structure and safety stands before revolving the tracks.
• Take care when measuring hot hydraulic oil flows to avoid high-pressure injection injuries.

Required Tools

• Hydraulic gauge test set (up to 6000 psi / 400 bar)
• Flow meter or volume measuring beaker
• Line capping and plugging plugs

People Also Ask

• Why is my Kubota KX057-4 drifting to one side during dual-joystick travel?
• How do I perform a case drain flow test on a Kubota KX057-4 travel motor?
• What is the correct travel pilot line pressure specification for a Kubota KX057-4?
• How do you distinguish between a failed center swivel joint and a bad travel motor on a Kubota excavator?
• Can a malfunctioning dual-velocity travel solenoid cause weak tracking on one side of a KX057-4?
• How do I check for internal bypass in a Kubota KX057-4 final drive motor?

Related Guides

Suggested Follow-Up Guides

• Kubota KX057-4 Center Swivel Joint Rebuild and Seal Replacement Guide
• How to Perform a Hydraulic Case Drain Test on Kubota KX-Series Excavators
• Kubota KX057-4 Main Hydraulic Pump Flow and Pressure Testing Procedure
• Kubota KX057-4 Hydraulic Control Valve Travel Spool Troubleshooting
• Diagnostic Guide: Kubota Two-Speed Travel Solenoid Valve Failure

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