Winch from rear end

[CalG]

Yes, in an open differential, with a constant input speed, if you stop one axle the spider gears start spinning and the other axle will be spinning at twice the speed it was before.

There is always the compromise condition of only enough pull as needed to shift the load.

100% lock up of the off side is not always required.

torque and speed are traded in the case of an open diff.....

 

[R W]

I . Your winch needs to pull from centerline of your pulling unit.

I strongly agree. If using a diff set up, would bring the drum onto centre by using an extra shaft (+bearings) driven from one end of the diff by sprockets & chain.

 

[square1]

Have to admit I was fully expecting to see this when i opened this thread:



Instead I find something useful

 

[muddstopper]

Well, if I was going to use a car rearend, here is how I would do it. Remove axle from one side completely, you dont need it. Saw off axle tube and weld a cap to contain oil. How short you cut the axle tube depend on how you intend to mount the winch and how you engineer the mount. Weld spider gears to make a solid locker differential. Machine pinion yoke to recieve a large 100 size roller chain sprocket and a smaller tooth count sprocket on the pto shaft. The ratio of the sprockets would take into consideration of the ring and pinion of the rear end used, but options would be just about unlimited. Make a cable drum to mount on the axle side of rearend and use the tractor clutch and pto engage lever to run the winch. If you leave the brake drum on the spool mount, you can adjust the brake shoes to provide tension to prevent free wheel run off of the cable while you are pulling the cable off the spool. We used a similar set up as I described for years on the back of a dexter tractor as a logging skidder, and I have seen dozens of similar setups being used by others. Winches are fast and strong. We have skidded 100ft tall whitepines up steep mountain sides without having to buck into shorter lenghts, sometimes winching 200ft before getting the trees close enough to the tractor to attach chokers to skid with.

 

[bcp]

Is there a common (cheap) independent rear suspension differential that would work without all the modifications needed to use a rigid drive axle?

Subaru comes to mind.



What else?

Bruce

 

[muddstopper]

Yes, in an open differential, with a constant input speed, if you stop one axle the spider gears start spinning and the other axle will be spinning at twice the speed it was before.

Just found a video that shows it, if you notice the free axle is turning faster then the carrier and ring gear.

Differential Action One Wheel Stopped - YouTube

I see what you are saying, but dont agree with your assessment of the speed or gear ratio. The gearing is determined by the ring gear and the pinion. The axle gears and the spider gears just connect the two axles to the gearing of the ring and pinion. To check the gear ratio, jack both wheels off the ground and let both spin freely. rotate pinon and count the rotations of the wheel in relationship to the pinion. Now block one wheel so only one will spin. Turn the pinion and count the rotation of the pinion and the wheel and you will see that the gear ratio is the same. Slippage of one wheel will not change the axle ratio, it only allows one wheel to slip as you are turning the vehicle around a radius. Now with axle still off the ground, place engine in park and turn one wheel and you will see that one wheel turn forward and one wheel turns backwards and the pinion remains stationary. Both wheels will turn a equal number of rotations, just in opposite directions, which is result of the spider gears being driven by the axle gears, and one wont turn without the other turning in an equal opposite direction.

Your video shows one axle locked, it doesnot show a speed difference between the axles if both are allowed to spin freely. If both axles where allowed to spin freely, the axle gears and spider gears will remain stationary and the entire differential mass would rotate at the same speed as the ring gear. If one axle encounters resistance, then the axle and spider gears will start to rotate allowing slippage of that axle (slower rotation), but the other axle, without the resistance, would still rotate at the same rate as the ring gear.

 

[CalG]

Muddstopper

You are on the right track, but have some of the details "flopped". In particular, the open diff does not so much allow the wheel with more traction to slow down, it allows the wheel with the least traction to speed up! A subtle but important distinction. And the exact reason that with one axle locked to ground (but not to the internal carrier) the more freely turning shaft will see an increase on rotational velocity. 2:1 at the extreme.

There are very sophisticated multi stage differential drives that actually power the spider carrier to achieve some very interesting performance. Like turning in one spot. (Your fwd and reverse rotation observation) IIRC such devices might be found on a military tank.

Using an automotive diff. with welded spiders in order to make a right angle drive is OK, but there is no fun in it ;-)

 

[CalG]

Is there a common (cheap) independent rear suspension differential that would work without all the modifications needed to use a rigid drive axle?

Subaru comes to mind.

View attachment 371002 View attachment 371003


What else?

Bruce

If one were out "scrounging" Be sure to take along the drive shaft and both half shafts! Save a trip for the required spline fittings. That is why I suggested the BMW or the AUDI rear ends. Bolt on flanges! I'm sure there are others, but I'm not a car guy....

 

[muddstopper]

Muddstopper

You are on the right track, but have some of the details "flopped". In particular, the open diff does not so much allow the wheel with more traction to slow down, it allows the wheel with the least traction to speed up! A subtle but important distinction. And the exact reason that with one axle locked to ground (but not to the internal carrier) the more freely turning shaft will see an increase on rotational velocity. 2:1 at the extreme.

There are very sophisticated multi stage differential drives that actually power the spider carrier to achieve some very interesting performance. Like turning in one spot. (Your fwd and reverse rotation observation) IIRC such devices might be found on a military tank.

Using an automotive diff. with welded spiders in order to make a right angle drive is OK, but there is no fun in it ;-)

What you are saying is that a rear end with a 4:10 to 1 ring and pinion ratio is only 4:10 to 1 ratio if both wheels are turning. Stop one wheel and it becomes a 2:5 to 1 ratio. I aint buying it.

In any event, if one plans on using a rear end to make a winch, welding the spider gears to make a posilock diff. is the simplest method. We call them hobart lockers.

 

[plumbstraight]

Tell you this Mudstopper. Jack up a car on one side. Rotate the driveshaft Say three and a half revs. Make a mark on the tire and see how many times it goes around with the other one on the ground. Tell us the ending results, maybe we can buy that.