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The TL140 and Its Auxiliary Hydraulic System
The Takeuchi TL140 compact track loader was introduced in the mid-2000s as a robust, high-performance machine for grading, lifting, and attachment work. With an operating weight of around 8,600 lbs and a 81 hp engine, it quickly became popular among contractors for its durability and hydraulic power. One of its key features is the auxiliary hydraulic circuit, which allows operators to run attachments like grapples, 4-in-1 buckets, and augers.
The TL140 uses a proportional valve bank to control auxiliary flow, with solenoids actuated by cab-mounted switches. These solenoids direct hydraulic fluid through two half-inch lines—typically labeled A1 and A2—for bi-directional flow. When functioning properly, the system allows attachments to open and close, rotate, or extend and retract.
Symptoms of One-Way Hydraulic Failure
In some cases, operators report that attachments only function in one direction. For example:
Initial Diagnosis and Solenoid Replacement
The first step is to inspect the solenoids on the proportional valve block. If one solenoid fails to energize or actuate, it may prevent flow in that direction. In one documented case, the operator replaced the non-functioning solenoid, but the issue persisted. The solenoid clicked when activated, but no fluid reached the A2 line.
This indicates that the problem may lie deeper—either in the wiring, the valve spool itself, or the control logic.
Mechanical vs Electrical Faults
To isolate the issue:
Cab Switch Configuration and Hydraulic Mode Selection
On the TL140, auxiliary hydraulic mode is controlled by two switches located behind the left joystick tower. These switches toggle between one-way and two-way hydraulic flow. For attachments like grapples or 4-in-1 buckets, both switches must be in the “up” position to enable bi-directional flow.
If one switch is depressed or unlit, the system may default to one-way flow—typically used for hydraulic breakers or augers that only require pressure in one direction.
Operators should:
In one scenario, a neighbor’s grapple worked fine on the same machine a month earlier, but now only opens or closes depending on line reversal. This raises the question of whether the attachment’s cylinders are worn or leaking internally.
If the cylinder seals are degraded, it may take less pressure to move the grapple, masking a weak hydraulic signal. Conversely, a heavier or newer attachment may require full pressure in both directions, exposing the fault.
To test:
To restore full auxiliary function:
Conclusion
One-way auxiliary hydraulic flow on the Takeuchi TL140 is often caused by a combination of electrical misconfiguration, solenoid failure, or valve spool obstruction. While replacing the solenoid may seem like the obvious fix, deeper inspection of the control switches, wiring, and valve internals is often required. With methodical testing and attention to cab settings, the TL140 can return to full functionality—ready to power the attachments that make it a jobsite workhorse.
The Takeuchi TL140 compact track loader was introduced in the mid-2000s as a robust, high-performance machine for grading, lifting, and attachment work. With an operating weight of around 8,600 lbs and a 81 hp engine, it quickly became popular among contractors for its durability and hydraulic power. One of its key features is the auxiliary hydraulic circuit, which allows operators to run attachments like grapples, 4-in-1 buckets, and augers.
The TL140 uses a proportional valve bank to control auxiliary flow, with solenoids actuated by cab-mounted switches. These solenoids direct hydraulic fluid through two half-inch lines—typically labeled A1 and A2—for bi-directional flow. When functioning properly, the system allows attachments to open and close, rotate, or extend and retract.
Symptoms of One-Way Hydraulic Failure
In some cases, operators report that attachments only function in one direction. For example:
- A grapple opens but won’t close unless the hydraulic lines are reversed
- Pressing the A1 button loads the engine, indicating flow, but pressing A2 results only in a click
- The 4-in-1 bucket closes under gravity but won’t open under pressure
- One solenoid appears active, while the other shows no response
Initial Diagnosis and Solenoid Replacement
The first step is to inspect the solenoids on the proportional valve block. If one solenoid fails to energize or actuate, it may prevent flow in that direction. In one documented case, the operator replaced the non-functioning solenoid, but the issue persisted. The solenoid clicked when activated, but no fluid reached the A2 line.
This indicates that the problem may lie deeper—either in the wiring, the valve spool itself, or the control logic.
Mechanical vs Electrical Faults
To isolate the issue:
- Confirm voltage at the solenoid connector using a multimeter
- Swap solenoids between A1 and A2 positions to test functionality
- Manually actuate the valve spool to check for mechanical binding
- Inspect the wiring harness for abrasion or corrosion near the joystick tower
- Check the fuse and relay panel for faults related to auxiliary hydraulics
Cab Switch Configuration and Hydraulic Mode Selection
On the TL140, auxiliary hydraulic mode is controlled by two switches located behind the left joystick tower. These switches toggle between one-way and two-way hydraulic flow. For attachments like grapples or 4-in-1 buckets, both switches must be in the “up” position to enable bi-directional flow.
If one switch is depressed or unlit, the system may default to one-way flow—typically used for hydraulic breakers or augers that only require pressure in one direction.
Operators should:
- Verify both switches are in the correct position
- Confirm indicator lights are functioning
- Cycle the switches to reset the control logic
- Refer to the operator’s manual for switch behavior and override procedures
In one scenario, a neighbor’s grapple worked fine on the same machine a month earlier, but now only opens or closes depending on line reversal. This raises the question of whether the attachment’s cylinders are worn or leaking internally.
If the cylinder seals are degraded, it may take less pressure to move the grapple, masking a weak hydraulic signal. Conversely, a heavier or newer attachment may require full pressure in both directions, exposing the fault.
To test:
- Connect a known-good attachment and observe behavior
- Use a pressure gauge on both A1 and A2 lines during actuation
- Check for internal leakage by observing cylinder drift when idle
To restore full auxiliary function:
- Clean and inspect the proportional valve block
- Replace or rebuild the valve spool if sticking is confirmed
- Verify solenoid coil resistance and replace if out of spec
- Inspect and repair wiring from cab switches to valve bank
- Flush the hydraulic system to remove contaminants
- Train operators on switch configuration and attachment compatibility
Conclusion
One-way auxiliary hydraulic flow on the Takeuchi TL140 is often caused by a combination of electrical misconfiguration, solenoid failure, or valve spool obstruction. While replacing the solenoid may seem like the obvious fix, deeper inspection of the control switches, wiring, and valve internals is often required. With methodical testing and attention to cab settings, the TL140 can return to full functionality—ready to power the attachments that make it a jobsite workhorse.
