Manitou MT932 Telehandler Series 1

[Bobthebuilder]

Can anyone give me a steer on this issue please. I appear to have an intermittent fault on my manitou MT932 tele handler. Sometimes when you slide the forward/reverse selector in to reverse, nothing happens. If you slide it in to forward travel the machine takes up drive and applies power to the wheels as expected. I have a feeling this may be an electrical problem but its intermittent and is going to be a sod to find. Can anyone tell me what physically happens down at the gearbox/torque converter when the travel lever is moved. Is there a solenoid or something on the torque converter/gearbox that I can check the voltage across to see if its actually getting power when the problem next occurs, probably when the machine is knee deep in sh!t.

[Muz]

I'm guessing there will some lock out shut offs too that could be involved .. is it more prevalent at a certain boom position ?

[Bobthebuilder]

I'm guessing there will some lock out shut offs too that could be involved .. is it more prevalent at a certain boom position ?

No, I don't think so. There are three 'travel' relays on a circuit board under the dash, one activates when forward is selected on the travel lever, the other when reverse is selected. From what I can work out, the 'reverse relay' does not always energise (sometimes, without touching anything when the problem exists, you here a delayed click as the relay energises and the machine takes up drive to the wheels. Sometimes the delay lasts ages sometimes seconds, sometimes the relay never clicks and you have to move the travel switch to neutral then back again. Its like the relay is sticking?

As far as interlocks go, the handbrake has a micro switch which de-energises both travel relays as you would expect. As it is only reverse travel that exhibits this intermittent fault, I tend to feel it is not the handbrake microswitch (forward would be affected as well otherwise). The only other potential interlock is the brake pedal microswitch which together with a transmission inhibit switch on the dash acts to either remove drive when the brake is pressed OR remove drive when the hydraulics are being operated (depending on the position of this switch). As all three relays are the same, I swopped forward and reverse thinking that if it was a relay issue, I would now loose forward instead of reverse. The outcome of this little experiment is that I still intermittently loose reverse. I'm now trying to work out how the third relay works and am thinking of swapping it with one of the other two.WK00182.jpg

[Muz]

The only other potential interlock is the brake pedal microswitch which together with a transmission inhibit switch on the dash acts to either remove drive when the brake is pressed OR remove drive when the hydraulics are being operated (depending on the position of this switch). As all three relays are the same, I swopped forward and reverse thinking that if it was a relay issue, I would now loose forward instead of reverse. The outcome of this little experiment is that I still intermittently loose reverse. [ATTACH=CONFIG]2090[/ATTACH]

Ok well that was logical thinking.. so the relays are eliminated (as we suspect) but .. Ive had experience of a park relay holding on when it shouldnt , but it controls forward and reverse usually which gets me to thinking a couple of things, were you certain all the relays you swapped were doing the same function even if they had the same base pattern ? also..keeping it simple ... is the fwd reverse shuttle stalk buggered ? or working ok for certain ?

[Bobthebuilder]

Ok well that was logical thinking.. so the relays are eliminated (as we suspect) but .. Ive had experience of a park relay holding on when it shouldnt , but it controls forward and reverse usually which gets me to thinking a couple of things, were you certain all the relays you swapped were doing the same function even if they had the same base pattern ? also..keeping it simple ... is the fwd reverse shuttle stalk buggered ? or working ok for certain ?

Relays are identical - I'm certain. I have already taken apart the travel lever and completely refurbished it. A new one was £120 on ebay and even then I couldnt be sure it was the right one. I replaced a spring and cleaned the contacts with contact cleaner. I then thoroughly tested all the switch contacts with a meter to make sure it all worked properly - its definitely not the stalk.