John Deere 4040

This is my John Deere 4040. I bought her a few years ago for no particular reason but she earns her keep by doing a bit of slashing and pulling out the odd stump.



She is a bit special because she has Power Front Wheel Drive, in which the front wheels are driven by hydraulic motors. This option wasn't very common and even less understood. The front wheels were only there to provide assistance and due to the nature of their operation, the wheels wouldn't spin if the tractor was bogged, but they would still apply full torque to the ground. Another oddity is the fact that the pressure relief valve was external to the motor so that if the relief valve opened, oil sprayed all over the tractor. A lot of these axles were scrapped as people thought the motors were worn out because they had excessive leakage to the case drain, resulting in the relief valves opening, but this was quite often a symptom of something much less serious. Mine had the PFWD control bank disconnected when I got it, but when I hooked it up, both the relief valves opened. I tracked down the problem to a leaking 'o' ring in the control bank letting pressurised oil go up both the supply and return hoses to the motor at the same time.



Anyway, I am starting a new business venture so I am pulling the old girl out of retirement to help get things off the ground. This means fixing a few problems....

Never knew they had that type of Drive. I've only ever seen the MFWD versions..

sugar cane farmers liked them as they had extra clearance and a lot of farmers up here worked 3 drills at a time and would widen them out to 10 foot centers
Oh and they turn nice and sharp still like a 2 WD

Paul

Here is a better view of the front axle.



As Paul said, lots of clearance and a tight turning circle. The PFWD utilised most of the 2WD steering components and axle beam. Inside the hub, the hydraulic motor turns a planetary gear set but the gear set drives the hub through a brake, which locks the gear set to the hub only when the hydraulic motor is turning. This means when 2WD is selected, nothing turns except the actual wheel hub. In PFWD mode, there are two settings- normal and high torque. In the normal mode, oil is directed to each motor separately, allowing the wheels to turn at different speeds. In the high torque mode, oil is directed to one motor and then across to the other, before returning. This ensures both wheels turn at the same speed with equal traction. The different modes and direction are controlled by electric solenoids in the control block.



Tractors with PFWD utilise a very large hydraulic pump and oil for the front axle is taken directly from the pump to ensure maximum power. Another advantage to having the large pump is having super fast, high flow hydraulics for a loader or other external services, when the front axle is switched off.

Even more interesting is the fact that even though this design is approaching 50 years old, John Deere released some 6WD graders about 10 years ago and they used the exact same system with the exact same parts to power the front axle.

The first job I had to undertake was replacing the main hydraulic pump. Unlike the majority of John Deere's of this vintage, the PFWD hydraulic pump is driven by a heavy duty taper lock splined coupling as opposed to the normal clamped spline drive.



At some stage, due to a dodgy crankshaft dampner, the taper lock came loose and broke a piece out of the pump shaft and chewed the teeth out of the coupling.



The worst thing about it was the pump was not that old and had not done a lot of work, and the decision was made to replace the pump shaft and coupling, so I set about removing the pump......

Loving this, learn something new here all the time.

Jarrod.

I dont know much about these I know they never sold a bucket load of them which I think had more to do with peoples lack of understanding how they worked
Because you very rarely see the front wheels spin I think people assume that they didnt help much but people I know of who have these reckon they are great
The wreckers up here did have a complete front end sitting there out on 10 foot centers had been there for years but a fella I new that has one of these was buying it or some such thing

Paul

I drove a 2130 in Melbourne years ago for ACE Contractors. We used it for slashing blocks on steep country (Ferny Creek,Olinda and Selby)in the fire season. It tended to spin the front wheels when it broke traction and spray mud and dirt over the driver. It was great steering it going up hill. The 2 wheel drives could only be steered with the turning brakes going up steep. The 2130 would pull the tractor around as the wheels were always trying a bit harder than the rears.