Cat AP1055D

[Brian Gokool]

The left track is much slower than the right track, the machine is currently floating and even with the override switch, the right track is much faster.

 

[Paver mechanic]

Any fault codes?I would start with a piston pump neutral test. Then a pump synchronization test. Then a calibration of the pump EDC. How many hours on the paver? Serial number?

 

[Brian Gokool]

I don't have a scan tool available atm so fault codes I can't see. I've had caterpillar technicians take a look at it but they themselves have no clue as to what could be the issue, they suggested that it may be the propel motor. The hours are 4168.1 and serial number CATAP105VFAC00999

 

[BigWrench55]

How much did cat charge to say I don't know?

 

[Brian Gokool]

Well I'm still awaiting that service charge. Seeing that they didn't get the machine going, I'm assuming thats why they didn't send over any bills

 

[BigWrench55]

I know nothing about your machine. But I will assume that the track motors are controlled by a pwm solenoid valve. And if the hydraulic system is healthy then you are left with those solenoid valves and calibration. One thing that you can try is to remove the case drain hose from the effected drive motor and have a helper operate it. You shouldn't see anything more than a slight stream of oil coming out of the motor. If you see a lot coming out. Say like you can fill a gallon bucket quickly. Then the problem is in the motor. I will also assume that these tracks are powered by a closed loop hydrostatic transmission system. The pump that supplies the oil to the track motors is where the pwm valve will be. It is possible that the valve has a lever that you can manually operate and make one track or the other move. If that is the case then take extreme caution to not just reach in there and toggle those levers. You don't want to run yourself or someone over. Or have the machine swing into something. Any way raise the machine off the ground and operate each track three revolutions and time how long it will take for each track. If both tracks take the same amount of time and operate at the same speed. Then the problem is likely the valve that you just operated manually.

 

[Nige]

Well I'm still awaiting that service charge. Seeing that they didn't get the machine going, I'm assuming thats why they didn't send over any bills

there would still be labour & mileage charges for the dealer guy. I'm guessing it's not a "no fix, no pay" type of repair.

Did they at least hook their laptop up to it and check for Diagnostic Codes, etc, etc..?

 

[Brian Gokool]

I know nothing about your machine. But I will assume that the track motors are controlled by a pwm solenoid valve. And if the hydraulic system is healthy then you are left with those solenoid valves and calibration. One thing that you can try is to remove the case drain hose from the effected drive motor and have a helper operate it. You shouldn't see anything more than a slight stream of oil coming out of the motor. If you see a lot coming out. Say like you can fill a gallon bucket quickly. Then the problem is in the motor. I will also assume that these tracks are powered by a closed loop hydrostatic transmission system. The pump that supplies the oil to the track motors is where the pwm valve will be. It is possible that the valve has a lever that you can manually operate and make one track or the other move. If that is the case then take extreme caution to not just reach in there and toggle those levers. You don't want to run yourself or someone over. Or have the machine swing into something. Any way raise the machine off the ground and operate each track three revolutions and time how long it will take for each track. If both tracks take the same amount of time and operate at the same speed. Then the problem is likely the valve that you just operated manually.

I'll give that a try today, thanks

 

[Brian Gokool]

there would still be labour & mileage charges for the dealer guy. I'm guessing it's not a "no fix, no pay" type of repair.

Did they at least hook their laptop up to it and check for Diagnostic Codes, etc, etc..?

They haven't sent anything yet so I'm not sure what's their policy, but they did plug in and said pressures are good for both sides, they did noticed a speed sensor code but changing it made no difference

 

[Nige]

they did noticed a speed sensor code but changing it made no difference

Changing the speed sensor would not necessarily be the first logical action for a technician to make as a result of a Diagnostic Code, especially someone working for a dealer.

The Code should have led them to a Troubleshooting Procedure in the manual. Carrying out that procedure step by step might throw up something else such as a wiring fault, etc, etc.
The fact that the sensor was changed (if I read your post right) would seem to indicate that in fact the sensor was not the issue and that in all likelihood the Diagnostic Code is still there.

Do you have any imemory what the Diagnostic Code was, or could you find out from the dealer.?
It was not 153-08 or 154-08 by any chance.?

 

[Brian Gokool]

Changing the speed sensor would not necessarily be the first logical action for a technician to make as a result of a Diagnostic Code, especially someone working for a dealer.

The Code should have led them to a Troubleshooting Procedure in the manual. Carrying out that procedure step by step might throw up something else such as a wiring fault, etc, etc.
The fact that the sensor was changed (if I read your post right) would seem to indicate that in fact the sensor was not the issue and that in all likelihood the Diagnostic Code is still there.

Do you have any imemory what the Diagnostic Code was, or could you find out from the dealer.?
It was not 153-08 or 154-08 by any chance.?

I pulled the codes off the display but it appears that they cleared the fault codes as all I have is the active code for the disconnected screed

 

[Brian Gokool]

I know nothing about your machine. But I will assume that the track motors are controlled by a pwm solenoid valve. And if the hydraulic system is healthy then you are left with those solenoid valves and calibration. One thing that you can try is to remove the case drain hose from the effected drive motor and have a helper operate it. You shouldn't see anything more than a slight stream of oil coming out of the motor. If you see a lot coming out. Say like you can fill a gallon bucket quickly. Then the problem is in the motor. I will also assume that these tracks are powered by a closed loop hydrostatic transmission system. The pump that supplies the oil to the track motors is where the pwm valve will be. It is possible that the valve has a lever that you can manually operate and make one track or the other move. If that is the case then take extreme caution to not just reach in there and toggle those levers. You don't want to run yourself or someone over. Or have the machine swing into something. Any way raise the machine off the ground and operate each track three revolutions and time how long it will take for each track. If both tracks take the same amount of time and operate at the same speed. Then the problem is likely the valve that you just operated manually.

I tried the case drain for both motors as you suggested, both sides for a period of 1 minute were dripping every few seconds

 

[BigWrench55]

Now we know that the motors are in good working order. What is left is the control side of the motors. Like I said above. I know nothing about your machine but you can try what I suggested. And if it isn’t as I say then I can’t add anything else.

 

[Brian Gokool]

Now we know that the motors are in good working order. What is left is the control side of the motors. Like I said above. I know nothing about your machine but you can try what I suggested. And if it isn’t as I say then I can’t add anything else.

Does the pwm solenoid valve have two coils to select for forward and reverse?

 

[BigWrench55]

At the propel pump (assuming it is as I think) there will be two pwm valves. One for each track and each will have a lever that when pulled in on direction. The track will either move forward or backwards. And when moved in the other direction the opposite. Follow your big hoses from the motor back to the propel pump or pumps. Also make sure that the side that is having the problem the park brake is releasing.

 

[TVA]

I’ll just leave my two cents here: if electronics and volumetric efficiency will check out to be OK - see the pressure differential between opposite sides of servo piston. Sometimes for few reasons there’s residual or leak pressure there, and servo piston not moving all the way.

Might wanna cross that possibility out of your list earlier, so you will not chance your own tail in case that’s what the problem is.

 

[Brian Gokool]

At the propel pump (assuming it is as I think) there will be two pwm valves. One for each track and each will have a lever that when pulled in on direction. The track will either move forward or backwards. And when moved in the other direction the opposite. Follow your big hoses from the motor back to the propel pump or pumps. Also make sure that the side that is having the problem the park brake is releasing.

I checked and there isn't any levers but I did I fact locate two manual bypass switches that overrides the parking brake and drives the machines. Upon using said switches the machine still behaved in the same manner

 

[Brian Gokool]

I’ll just leave my two cents here: if electronics and volumetric efficiency will check out to be OK - see the pressure differential between opposite sides of servo piston. Sometimes for few reasons there’s residual or leak pressure there, and servo piston not moving all the way.

Might wanna cross that possibility out of your list earlier, so you will not chance your own tail in case that’s what the problem is.

Thank you for your advice, I'll be trying that tomorrow