Excavator Lock Pin Stuck? Avoid Costly Repairs When Changing Attachments

  • Written by Luis
Komatsu excavator lock pin

Changing excavator attachments is a relatively easy process. However, inexperienced operators may find that they cannot remove the lock pin when trying to disengage the bucket from the wedge coupler.

This problem and other issues when changing attachments can create damages that will result in costly repair charges. Learn how to remove a stuck excavator pin and avoid other attachment mistakes by using the following steps.

Don't Make This Mistake! Avoid Costly Repairs When You Change Excavator Attachments
Solving a Stuck Excavator Lock Pin

If you are unsure about why the excavator pin is stuck, cannot ask anyone for the answers, and cannot review a video, here is the reason why it is occurring.

  1. Check whether the lock pin is loose. If it is, then everything is fitting correctly between the wedge coupler and bucket luging.
  2. The lock pin does not move. It means that the hydraulic force is pushing on the wedge. This problem occurs when the switch has been tripped.
  3. You need to reactivate the wedge coupler. Return to the cab and trip the switch so that the wedge coupler goes back into place to hold the bucket again. Check to make sure the bucket is squared to the ground.
  4. The lock pin should now be loose. Never remove the lock pin while the bucket is suspended in the air. It could hurt people or damage equipment.
Heavy duty mechanic demonstrating where to flip the switch to engage the excavator

Most if not all hydraulic couplers have a manual locking pin installed when the machine is in operation. It is a redundant safety measure since the hydraulics keep the bucket in place. The lock bar actually stops the wedge from coming back if the switch becomes tripped or there is a hydraulic failure. Even though it is redundant, the lock pin should still be in place at all times. When the lock pin is removed to switch out attachments, the safety pin should be connected to it and stored in a safe location where it can be seen.

Demonstrating where the lock pin is on a Komatsu excavator
What Else to Know About Excavator Attachments
  • Always wait 15-20 seconds when removing the attachment to avoid damaging the wedge car and bucket lugging.
  • Ensure that the wedge is fully disengaged before trying to attach the bucket. Visually check from your cab that the wedge is all on the left.
Demonstration of what a disengaged wedge looks like on an excavator
  • Listen for an audible cue that sounds like beeping to tell you that the wedge has been engaged disengaged. If you do not hear the beeping, the wedge has been engaged.
  • Attempting to line up the second lugging when the wedge is not fully disengaged will cause damage to the machine.
  • Make sure that 100% of contact is made on the backside of the coupler to the wedge bar. Otherwise, you will not have clearance and will cause damage to the bucket lugging and wedge. Also, too much oil will move through the hydraulic cylinder itself that can cause damage to the cylinder or blow a hydraulic hose.
  • Inexperienced operators should turn down the RPM when changing attachments.

If you are looking for more information about excavators, attachments, or how to install them correctly, reach out to Fortis HD.

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