Push the truck by rolling the tire? (1 Viewer)

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bpenn1980

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Maybe this is old news to all you guys out there, but this is tripping me out! So instead of leaning my shoulder into the truck and pushing like crazy, I can take one hand and EASILY move the truck by rolling the tire...


How does this work?
 
It is called mechanical advantage. Think of having a pry bar on the ground where the tire is touching the ground. You pry on that 35" bar(tire diameter) against the 17" axle housing. You are effectively doubling your input against the axle housing. I wouldn't say that you can easily push it, but it is twice as easy.
 
Well, no. Your 'pry bar' has a fulcrum 17" from each end, giving no mechanical advantage.

-Spike
 
Well, no. Your 'pry bar' has a fulcrum 17" from each end, giving no mechanical advantage.

-Spike

Well, how do you explain the decreased effort to push a vehicle by pushing on the top of the tire.
The axle is the fulcrum. The top of the tire is the point of work, and the ground is the fixed point.
 
For every two inches you push the top of the tire, the axle moves one inch. You have a 2:1 mechanical advantage.
 
For every two inches you push the top of the tire, the axle moves one inch. You have a 2:1 mechanical advantage.

This is correct.

Theoretically, only when pushing at the *exact* top of the tire.

Pushing at axle level would be equivalent to pushing on the body. And pushing at the bottom of the tire would of course accomplish nothing.

Curtis
 
Didnt realize this was a can of worms.

I saw the guy at Firestone do this, so I duplicated it.

I have to roll my truck about 3 feet backwards to open the hood when I'm in my parking space since I have cabinets. Rolling the truck forward again is usually really difficult even though its only a slight incline. Using the tire makes it very easy.
 
why not just start it Jack LeLane? :flipoff2:
 
This is not going to turn into this thread is it.

I'd been using the 3 and 9 o'clock positions to turn the tires for years. Pretty easy!!
 
It is true. When pushing dead cars into shops, it is much easier to push the wheel than the whole car. But the wheel moves faster and you have to be quicker! It is hand over hand as fast as you can.
When getting unstuck, it can be much more dangerous. When the pushed vehicle gets a grip, it can outrun you and run over you much faster than you can react! It has happened to me.
When I was 14 and my brother was 16, I learned this the hard way. His buggy, (1200 lbs.) was stuck in sand. I pushed the rear wheel. It worked all too well. The buggy got a grip and pulled my legs under the rear wheel! I had burn-out marks on my jeans at the knees! The car pulled out of the sand and I was sore for a couple of days. It was no big deal. I was 14 and resilient.
Now, several on top of several years later, I can tell you that this is not a good idea in any way! I have learned the secret of my own mortality. I am capable of becoming dead due to that kind of heroism! I learned.
We are not dealing with 1200 lb buggies anymore! We are working with nearly 3-ton Toyo 80's. I suggest that you do not play this game with this truck! If you try this, the 5700 pound truck will run you over. Human pushing on this truck will have little effect unless you are Herculean in strength. You are not. It is smarter to let the truck, tow straps and winches do the work. That is why we have them. Don't try to push a truck that weighs nearly 6,000 lbs. It will not work!
 

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