2007 3520 Power Reverser won't move

[radios1]

Can you post the theory of operation page(s)? That might help us understand the operation and better comment on where to look.

he wouldn't even say if he checked the reverser cable!!..

 

[tuolumne]

I'll try to post those pages. I have taken apart the entire PRT valve. There is no sign of any wear, anything stuck, any compromised o-rings....all looks pristine. Yet the lubrication pressure port measured zero. I plan to reassemble everything, put back on the machine and try again.

 

[tuolumne]

Here is the theory of operation.

 

[Zebrafive]

I'll try to post those pages. I have taken apart the entire PRT valve. There is no sign of any wear, anything stuck, any compromised o-rings....all looks pristine. Yet the lubrication pressure port measured zero. I plan to reassemble everything, put back on the machine and try again.

Four things could prevent a reading from the Lubrication port:
1 Orifice N is plugged
2 Lubrication relief valve O is stuck open
3 Lubrication shutoff valve M not opening (stuck closed)?
4 Modulation valve P not opening



3

 

[xrjohndeere]

3520 with 3000+ hours. Lots of loader work and woods work. Transmission has been flawless until now. There has been no slow change or accident; just sudden failure.

First, does anyone have access to a service manual?

This machine won't engage forward or reverse. The linkage is working fine (moves lever on the side of the transmission). The clutch linkage is fine. The machine starts fine (not safety switch). The hydraulics are working fine - loader and rear implement operate smoothly and with normal power. The 3 point lifts normally, but I cannot speak for its strength with no 3PH implement attached. All fuses are good.

The dealer suggested a relay - thought there should be one labeled PRT, but there is not.

Dealer suggested o-ring failure on hydraulic loop that engages PRT - said pressure could be checked at a plugged port on the transmission. Where is such a port? The dealer did not suspect solenoid since both forward and reverse are out. Does that ring true? I have not yet been able to connect with a service tech on the phone.

The machine had been operating normally, backed up to load logs on a forwarder, then would not move again. The forwarder can push the machine forward and back, so the rear tires are turning freely.

Please offer your suggestions to help us get this machine back into operation.

Check your inline hydraulic filter screens. I bet they are stopped up.

 

[radios1]

a gear transmission would still be working!. yeah, hydrostatic transmissions have their drawbacks and repair costs!.. sorry it got you though..

 

[beenthere]

a gear transmission would still be working!. yeah, hydrostatic transmissions have their drawbacks and repair costs!.. sorry it got you though..

Am thinking the Power Reverser tranny is considered "gear", not HST.

 

[radios1]

Am thinking the Power Reverser tranny is considered "gear", not HST.

no, though.. somewhat.. the clutches are hydraulic, 12F/12R PowrReverser™ transmission is ideal for heavy applications

 

[tuolumne]

he wouldn't even say if he checked the reverser cable!!..

There is no reverser cable - it is a rod directly to the reverser valve body.

 

[tuolumne]

Check your inline hydraulic filter screens. I bet they are stopped up.

The machine has new hyrdraulic oil, new suction filter, new inline filters.