Powering an idler axle

[bcp]

I wonder how well this works.

Tractor version
jodh on tracter - YouTube

Truck version:
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Bruce

 

[brokenot]

For its intended purpose it actually works quite well. If you think about it, the contact patch between the tire and the road isn't much bigger than the contact patch between the powered "friction drive" wheel and the tire. If the friction driver is pushed against the tire with enough force to prevent slippage, you can transfer loads of driving torque.

We have a couple of these towable boom lifts in rental. The user tows it to their location, disconnects it from the tow vehicle and then drives it around by using the onboard friction drive apparatus. Each friction driver has its own hydraulic motor, and the unit is driven and steered around with a small joystick. There are no issues with wheel slippage whatsoever. You can drive up steep driveways, over potholes, etc.:

Is it an appropriate setup to be employed as a "full-time" drive? Well, probably not. But as a "helper" drive? Absolutely.

At a motorcycle rally a few years ago, I saw a high-end custom bike being demo'd that had quite a crowd gathered as it blasted up and down the street. Gawking onlookers couldn't figure out what was driving the rear wheel. No shaft, belt, or chain in sight. The shop that put it together hid a friction drive roller up under the seat and concealed it with some bodywork. The drive roller simply mated against the rear tire to propel the bike down the road....

 

[Iplayfarmer]

How does a friction drive affect tire wear?

 

[brokenot]

How does a friction drive affect tire wear?

It really hasn't been an issue on the stuff I've seen. Oddly enough, the steel drivers seem to wear more than the tires. Here's a photo of an old Yazoo Big Wheel mower. Note the worn down center of the metal drivers...the driver "teeth" are straight across when new:

There are quite a few of these mowers still around, and many have the original rubber tires. They're weather-cracked and barely hold air, but they've been on since new. The drive rollers on the other hand, have either been replaced a couple of times, or they're so worn down in the center that they slip....turning the "self-propelled" feature into more of a "propel assist".

 

[Renze]

How does a friction drive affect tire wear?

It causes less tire wear than spinning your drivewheels every day.

I think its called a Robson drive. pretty much standard equipment on 6x2 tandem container trucks around here.

The hydraulic front wheel assist, i posted some links to MAN hydro drive videos last week in another thread: MAN developed this in cooperation with Poclain hydraulics. It uses orbit motors, which pistons simply are pushed back to neutral when the wheels freewheel. It therefor doesnt have drag losses at highway speeds, weighs 400kg less, and you can use a conventional drop axle beam, instead of a straight axle with differential bellhousing under the engine crankcase.

MAN HydroDrive. More traction in every situation. (part 1) - YouTube
MAN Trucks_Hydrodrive - YouTube
Its great to give that little push.

But for real offroading, you need a Tatra with independent wheel suspension:
http://www.youtube.com/watch?v=NjLtO5msx1M&feature=related
www.tatraphoenix.com

their chassis technology dates back to 1928:
http://www.youtube.com/watch?v=9ursLDiSUEo

 

[turnkey4099]

It would be nice to have one of those as a 2-wheel, stand-alone unit with a trailer hitch on the front. Be fabulous for moving my splitter, wood carts, wagons, etc around. Lot easier to get them into position by pushing rather than towing and then backing them in.

Harry K