Buying Advice How do you check to make sure 4WD works?

[ah64_ip29]

Is there an easy way to make sure 4WD is working during a test drive? I'm looking at older models that have a pull knob on the floor to the left of the seat.

 

[JasG]

Drive the tractor in 2wd and make a a couple of sharp turns, next do it in 4wd. Not a perfect test but you should notice a difference. If it has a loader on it you could lift the front end off the ground and with helper try and spin the tires with the machine parked, but the 4wd locked in.

 

[ah64_ip29]

Maybe a stupid question, but I've looked at both a Ford 6600 and a Kubota m9000 with this box, and both times the guys selling them didn't know how to engage it. They'd jumped on a local tractor for cheap to turn around and resell online. Do you pull up or push it down to engage the drive?

The one did have a loader, so I could try that.

 

[brandoro]

Chain the drawbar to an immovable object and carefully try to move the tractor forward with the control in one position then the other. In one position one or both rear tires should turn along with one or both front tires, in the other position the rear tire(s) should move but not the front.
If you engage the differential lock both rear tires should turn.
The reason I say "carefully" above is that even when hooked to the drawbar there is a posibility for the front end to lift. Go slow, low RPM ready to stop. Never hook to anything higher than the drawbar for pulling.
Or as mentioned above try turning sharply with the control in both positions and see how the front wheels react. In two wheel drive the turn should be smooth, in four wheel drive the front tires will turn skid turn skid in small lurches.

 

[RickB]

Drive the tractor in 2wd and make a a couple of sharp turns, next do it in 4wd. Not a perfect test but you should notice a difference. If it has a loader on it you could lift the front end off the ground and with helper try and spin the tires with the machine parked, but the 4wd locked in.

That is a perfect test. If one knows what 'feel' to check for, and checks the disturbance a tire makes, this test is valid. Additionally, for electric over hydraulic MFD clutches, switching off the MFD during a hard turn will make the tractor lunge when the MFD clutch disengages.

 

[RoyJackson]

Chain the drawbar to an immovable object and carefully try to move the tractor forward with the control in one position then the other. In one position one or both rear tires should turn along with one or both front tires, in the other position the rear tire(s) should move but not the front.
If you engage the differential lock both rear tires should turn.
The reason I say "carefully" above is that even when hooked to the drawbar there is a posibility for the front end to lift. Go slow, low RPM ready to stop. Never hook to anything higher than the drawbar for pulling.

Although a great method, I doubt if too many owners or any dealers would let you try it.

Engaging 4WD and watching or feeling for that difference (described by other TBNers) is the way I've done it.
The dealer that sold me my first tractor had a slope (short, but steep) you could climb...that was a really good test, IMHO. That's also when most of their customers were agricultural and had some knowledge of machinery. Now, mostly residential (although they still sell bigger equipment) and that slope is fenced in.

 

[CurlyDave]

Drive it on some concrete with 4WD engaged.

If 4WD is working there is a slight difference between rotation speed of front & rear wheels and you will leave visible tire marks on the concrete.

 

[DavesTractor]

Put it in 2wd and drive at 5-10 MPH on some surface that doesn't give great traction (loose gravel, grassy field) and hit the brakes, the tractor will skid the rears tires but not stop quickly. Now put it in 4wd and do the same. There is a huge difference as the tractor will stop quickly.

You can also lift the front end with the bucket, high enough to get both tires in the air, then slowly back up and see if the front tires seem like they are under power.

 

[RickB]

Put it in 2wd and drive at 5-10 MPH on some surface that doesn't give great traction (loose gravel, grassy field) and hit the brakes, the tractor will skid the rears tires but not stop quickly. Now put it in 4wd and do the same. There is a huge difference as the tractor will stop quickly. .

Many larger tractors engage MFD when both brakes are applied.

You can also lift the front end with the bucket, high enough to get both tires in the air, then slowly back up and see if the front tires seem like they are under power.

Many MFD clutches have enough drag when disengaged to invalidate this test.

Both tests are OK for tractors with mechanical engagement of the MFD.

 

[DavesTractor]

Many larger tractors engage MFD when both brakes are applied.



Many MFD clutches have enough drag when disengaged to invalidate this test.

Both tests are OK for tractors with mechanical engagement of the MFD.

Thanks for clarification on that. These tests that I mentioned seem to work well with compact tractors with simple mechanical engagement. On more sophisticated systems, they could be misleading. Great comments, and I thank you.