CAT 130G 9Y Series Transmission Won't Shift

[andy.jobcorps]

Hello all, I've got a 1978 CAT 130G 9Y series grader with the 3304 engine that will not shift into either forward or reverse at any speed. Main Hydraulics work fine. So far I have checked:
Transmission Oil - Full
Transmission Filter - Replaced
Transmission pump pressure - low 250 PSI, added another spacer to relief valve group, now 300 psi
Shift cable - connected at both ends
Manual Modulation Cable - connected at both ends
Forward/Reverse Cable - connected at both ends

Any ideas you have would be appreciated. Thanks.

 

[r20d12]

If the modulation pedal is malfunctioning. It will not let clutches engage. Make sure everything moves free. Actually take the cable loose on both ends and slide it back and forth by hand and make sure pedal is all the way up. Then check clutch pressures.

Hope this helps

 

[Nige]

Did you take a look inside the old filter or in the suction screen to see if there were any clutch material paritcles in there..?

 

[20/80]

Hello all, I've got a 1978 CAT 130G 9Y series grader with the 3304 engine that will not shift into either forward or reverse at any speed. Main Hydraulics work fine. So far I have checked:
Transmission Oil - Full
Transmission Filter - Replaced
Transmission pump pressure - low 250 PSI, added another spacer to relief valve group, now 300 psi
Shift cable - connected at both ends
Manual Modulation Cable - connected at both ends
Forward/Reverse Cable - connected at both ends

Any ideas you have would be appreciated. Thanks.

What were you doing when you lost your gears? did this happen while grading or working your machine? or was the machine sitting for awhile and now your gears don't work?

 

[andy.jobcorps]

What were you doing when you lost your gears? did this happen while grading or working your machine? or was the machine sitting for awhile and now your gears don't work?

Operator reported that it came to stop on its own while grading, put it in reverse where it sluggishly rolled a bit then was dead in the water.

 

[r20d12]

Sounds like you need to check pressures and then inspect the magnetic screen.

 

[andy.jobcorps]

Ok, we think we figured it out. it appears the pilot pressure tap plug at the top of the XMSN valve bank fell out in operation and is allowing the pressure to dump out of the valve.

Troubleshooting steps to date:
-Oil level checked - full
-XMSN Filter changed - old filter relatively clean
-checked all pressure taps except pilot pressure tap (difficult to access)
-Pressures - see table
-drained oil and dragged a magnet through it - clean
-the tap P2 for the direction clutch was 0 psi when it should have been approx. 200-250 psi (our pressure gauges had 30 psi error) that led us to valve level three to check the differential, safety and check valve - everything was fine
-since we had it out we disassembled and inspected the entire valve bank. - everything was fine
-at this point we were running out of easy checks and took another look at the book. forgot to check the debris screens.
-bottom debris screen had the plug for the pilot tap in it as shown in pics below - should have checked debris screen first.

it also looks like the speed clutch is starting to wear out as there were a number of bronze flakes in the screen as well.
We're still putting it back together and have yet to test it; should know tomorrow. Thanks for the help everyone.

 

[Nige]

Can you post some better photos of the brass particles that came out of the magnetic screen..?

 

[andy.jobcorps]

The plug fixed the problem! It moves in all gears and directions.

 

[andy.jobcorps]

Can you post some better photos of the brass particles that came out of the magnetic screen..?

Here you go.

 

[Nige]

The dark pieces appear to be clutch material. Not sure about the source of the brass ones though. Could even be differential. Just to be clear, on this machine there are two identical screens, one (upper) for the differential & bevel gear compartment, the other (lower) for the transmission. Which of the two did these particles come from..?

Maybe run the machine for a while and pull the screens again to see what has accumulated.

 

[d9gdon]

That's great. I can never get that lucky on a breakdown!

 

[HARRIS*1]

Ok, we think we figured it out. it appears the pilot pressure tap plug at the top of the XMSN valve bank fell out in operation and is allowing the pressure to dump out of the valve.

Troubleshooting steps to date:
-Oil level checked - full
-XMSN Filter changed - old filter relatively clean
-checked all pressure taps except pilot pressure tap (difficult to access)
-Pressures - see table
-drained oil and dragged a magnet through it - clean
-the tap P2 for the direction clutch was 0 psi when it should have been approx. 200-250 psi (our pressure gauges had 30 psi error) that led us to valve level three to check the differential, safety and check valve - everything was fine
-since we had it out we disassembled and inspected the entire valve bank. - everything was fine
-at this point we were running out of easy checks and took another look at the book. forgot to check the debris screens.
-bottom debris screen had the plug for the pilot tap in it as shown in pics below - should have checked debris screen first.

it also looks like the speed clutch is starting to wear out as there were a number of bronze flakes in the screen as well.
We're still putting it back together and have yet to test it; should know tomorrow. Thanks for the help everyone.
View attachment 182417
View attachment 182414 View attachment 182415 View attachment 182416

When you removed the pilot selector and pressure control valve group was there a gasket? or when you re-install it do you put any sealant between it and the transmission where it is a machined surface? it just seems strange to have nothing there?

 

[Nige]

There is no gasket and the joints between the various sections of the transmission control valve do not use sealant. The oil passages are sealed separately so the body of the valve itself doesn't need sealing. Post a machine Serial Number for detailed information.