New Holland tl100

pauldnan

Hi there. I just got a 02 tl new holland which would be a step up from what I would have been used to so my knowledge would be very limited. I was wondering is it normal for the 4 wheel drive to come on when I hit the brakes. It just feels wrong to me as you could be doing a fair speed when this happens. It also then seems to try and disengage itself again when moving and getting some speed up and a loud rough sounding clunk seems to come from right rear axle. After doing some research some tractors have a 4 wheel drive braking system. Has anyone ever encountered this before. It just feels all wrong to me and unsafe. I drove plenty of newer hi spec tractors and don't remember this being an issue. Any answers or advice would be appreciated as I don't want to do any major damage to the transmission by thinking this is OK if it's not. Tia

Testacalda

Perfectly normal for the 4wd to engage when the brake is pressed, it's designed to. Nearly all modernish tractors do it, it's the easiest way to have 4 wheel braking as such.

Can be a nuisance when manoeuvering in tight spaces, especially on concrete. It should disengage within a second or 2 of letting your foot off the brake.

Also if you have the 4wd engaged, a lot of tractors will automatically disengage it when your reach a certain speed, eg 25 - 30kph

Are your tyres all evenly worn, tyre size mis-match or uneven wear back to front will make the disengagement of the 4wd harsh.

pauldnan

Thanks for your reply. All the tyres are good around 90 per cent. It was staying on until the tractor reached 5 or more kph the releasing with a loud clunk. Well it was its now staying in 4wd all the time. IV tried a few things but to no avail. I am waiting on a mechanic but there hard to get. Thanks for your advice tho

Testacalda

Could be electrical fault perhaps, check fuses to see if the one for the 4wd solenoid is blown. Some tractors will stay in 4wd of fuse is gone, However there seems to be an actual problem with your tractor.

mad-for-tar

Yes it’s normal. Switches on brake pedals linked to 4wd system that switch off power to the solenoid when brakes are applied. All 4wd systems in general are spring applied and hydraulic released meaning you need to have hydraulic pressure applied to the clutch to disengage it.
On these it will be a crude dog clutch setup as opposed to a wet clutch that you’d have on more modern tractors. They have tendency to suffer from torque wind up that it takes a few metres for them to disengage after switching it off or releasing the brakes. You’ll probably find it disengages much faster if you go into reverse after switching it off or allow it to freewheel down a hill. Torque wind up usually a result of incorrect ratio between front and rear axle as a result you’ll always get a bit of a bang when it lets itself out of 4wd.
What tyre sizes have you on it?

If you’re 4wd is stuck on, there’s either a fuse blown, solenoid has failed, wiring issue or hydraulic supply issue to 4wd dog clutch. There is also a way around the 4wd braking by putting switches across the 2 middle terminals of each of the brake switches to keep signal in the 4wd circuit at all times via separate switch(es). Handy for the purpose of yard/loader work on concrete to prevent tyre scrubbing but you have to remember to switch it off before doing road work again.

Grueller

mad-for-tar wrote: »

Yes it’s normal. Switches on brake pedals linked to 4wd system that switch off power to the solenoid when brakes are applied. All 4wd systems in general are spring applied and hydraulic released meaning you need to have hydraulic pressure applied to the clutch to disengage it.
On these it will be a crude dog clutch setup as opposed to a wet clutch that you’d have on more modern tractors. They have tendency to suffer from torque wind up that it takes a few metres for them to disengage after switching it off or releasing the brakes. You’ll probably find it disengages much faster if you go into reverse after switching it off or allow it to freewheel down a hill. Torque wind up usually a result of incorrect ratio between front and rear axle as a result you’ll always get a bit of a bang when it lets itself out of 4wd.
What tyre sizes have you on it?

If you’re 4wd is stuck on, there’s either a fuse blown, solenoid has failed, wiring issue or hydraulic supply issue to 4wd dog clutch. There is also a way around the 4wd braking by putting switches across the 2 middle terminals of each of the brake switches to keep signal in the 4wd circuit at all times via separate switch(es). Handy for the purpose of yard/loader work on concrete to prevent tyre scrubbing but you have to remember to switch it off before doing road work again.

You’ll probably find it disengages much faster if you go into reverse after switching it off or allow it to freewheel down a hill. Torque wind up usually a result of incorrect ratio between front and rear axle as a result you’ll always get a bit of a bang when it lets itself out of 4wd.

I have a TL90 and always stop and reverse a couple of metres if I can when disengaging 4wd. It allows a much smoother switch off.

What tyre sizes have you on it?
Does this make much difference? I must check mine on the TL90 and post back here.

Testacalda

if the tyre size ratio is incorrect, it increases 'wind up' in the transmission, putting the meshing gears under more pressure, therefore making disengagement more difficult.

Even with the right size tyres, having a new set on the front, and a worn set on the back makes a noticeable difference, compared to a new set all around, that's on my TS115