Komatsu D37P-5 STEERING ISSUES

[TDJOHN]

The steering control valve under the joy stick seems to be malfunctioned, and advise? The dozer will bog down and when you wiggle the joystick it will track strait. same thing going forward.

 

[cbailey1956]

What do you mean "will bog down"? Is this the pilot controlled joystick? Should have small hydraulic lines out the bottom. Probably six lines. My D-31 has an adjustment procedure for centering the control if I remember right. Manual is not where I am now. How does the machine run overall, engine and track operation?

 

[TDJOHN]

The machine runs great, yesterday I adjusted the brakes again. When you go forward the dozer will not steer to the right, but in reverse it will steer both ways! The under carriage is 80 percent, if you put the dozer in reverse and start tracking it'll start to bog down and when you wiggle the joystick it does ok. It seems like the valve under the joystick may be bad. Komatsu ask $4,400.00 for a new control valve. I don't understand what the problem can be. Thanks for responding.

 

[J_J]

Is the joystick mechanical, cable operated, supplying a pilot flow, or electrical voltage to a solenoid operated valve.

You should be able to go beyond the joystick and test the valve with out the joystick.

If it is cable operated, check the cable assembly for smooth operation.

If it is hyd pilot operated, check the flow and pressure.

If it is electrical, apply voltage to a solenoid to see if things work correctly.

 

[J_J]

Is the joystick mechanical, cable operated, supplying a pilot flow, or electrical voltage to a solenoid operated valve.

You should be able to go beyond the joystick and test the valve with out the joystick.

If it is cable operated, check the cable assembly for smooth operation.

If it is hyd pilot operated, check the flow and pressure.

If it is electrical, apply voltage to a solenoid to see if things work correctly.

 

[cbailey1956]

First, it sounds like you have the manual steering bands a little tight. In reverse they might be pulling themselves tight and stopping the machine. I have adjusted mine and it easy to get them off. Does it turn left and right equally with hard turns and brake pedal depressed? The joystick lever (PPC valve) is adjusted by loosening the locknut at the bottom of the shaft and turning the contact plate untill it just touches the top of the 4 actuating rods that get depressed when moving the lever then tighten the locknut. Zero clearance but not depressing any rods. Is there any fluid linkage out of the joystick valve. When you say it wont steer right, does it steer right when using the brake pedal? You can troubleshoot the PPC valve by switching the 4 pilot lines on the bottom. Go clockwise one position on all four hoses and then check to see if the issue has changed. Yous PPC valve probably has P1,2,3,4 marked on the bottom for the 4 pilot functions. If the valve is acting up the machine will behave differently now. Be sure to have clearance around the machine when first running it with the lines moved until you know which joystick action is what. Hope that makes sense. The valve is repairable if defective. Just fine a good hydraulic shop if you are not inclined to look at it yourself.

 

[moose51992]

Ok im working on the d37p-5 for tdjohn and we rebuilt the ppc valve but when your tracking forward it wont turn right but in reverse it steers fine in both directions in forward it will only steer to the left it has self adjusting steering clutches and a hydroshift transmission-{direct drive}..... is it my pads are wore out?

 

[moose51992]

the ppc valve is ok now and i dont think its a pressure issue because it does fine in reverse its the same pressure in forward as it is reverse just the transmission changing directions so that rules out a pressure issue the only thing left i can think of is mechanical ....... brake pads?

 

[cbailey1956]

What is the serial #? The manual is broken down by model and serial#. What did you find while inside the PPC valve? How does it react to a hard right turn with the joystick while moving forward and the brake pedal is tapped? You say reverse has good steering? Does this include track locking and circling and also slow gradual direction changes? How does the oil look and smell? On my machine (6725 hours) I have had to start using the brake pedal along with the joystick to get a turn started at times. Remember the PPC valve is decreasing clutch pack pressure so one motor can slip and the other will drive to allow a turn. The foot brake applies a manual force.