pulling up on a wrench gives more force than pushi

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Nov 29, 2009
So I only weigh 120 and frequently can stand on a lug wrench and not budge the lug nut, but if I grab it with my hands and pull upwards on it I can pretty much loosen it with ease. I got to thinking, is it because the threads are slanted slightly, so it's creating a wedge in between the nut and the mating surface? So when you stand on it all downward force and friction make it harder to spin off?
I'm no engineer but I think I have better luck pushing down. It's all about which one gives you better leverage, so if you get more leverage pulling up, do that.
There is a reason you step on the Lug Wrench on the side of the road to crack the wheel nuts. Pushing with weight behind it is far more effective than pulling. Unless it's some weird contorted position.
Its because the torque you generate depends on how far you pull away from the axis of rotation (lug nut). That's how cheater bars work. The same force applies further from the rotation point gives more torque. The units for torque are ft-lbs or in-lbs. 1 lbs of force, 1 foot away from the rotation axis is 1 ft-lb of torque. move out 2 feet from the axis or rotation and apply the same 1 lb of force you get 2 ft-lbs. Stay at 1 ft from the rotation axis and apply 2 lb of force and you also get 2 ft-lbs. When you pull you generally grab the end farthest away from the bolt. When you stand you tend to get more towards the middle of the bar to fit your feet. That's also why a four-way wrench works better since you pull and push equal distances from the torque point so you double the torque.
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In certain instances: it's because you, personally, can apply more force with your muscles by pulling than you're capable of exerting just by bearing part of your body's weight on it. I weigh 160 and find plenty of times where I can get further with stubborn bolts by leveraging against something than just relying on my weight x leverage of the tool to do it.
OP, my experience is pretty much the same at 160. I think pulling up allows for more control than pushing down. The explanation above about where you hold the wrench probably has something to do with it. Also, pulling allows you to use your legs in addition to arms and back. I always try to use either a 4-way or a long torque wrench instead of the factory lug wrenches. I have to say, I've never tried standing on a lug wrench. That seems like a sure way to ruin the nuts and wind up on the ground.
Originally Posted By: bubbatime
You can probably lift 300-400 pounds using your muscles, which is obviously more than the 120 lbs you weigh.
Right, if you were to bend over and lift cinder blocks you're lifting most of your body (torso up at least) as well as the cinder blocks. Doing the lug wrench thing, you're probably lifting with your back, which will make you a cripple, but is done in life because it's effective.
I remove, and install a lot of wheels. I Always pull up on the wrench to loosen, and push down to tighten.
Originally Posted By: RhondaHonda
It means you can deadlift more than your body weight.
Ding ding ding! Yup Madman, you weigh 120, which means that when you stand on the wrench, the most you can apply is 120lbs at the point you're standing on it. My guess is that when doing this, you are not able to quite stand at the end of the wrench because of your center of mass, etc.. However, when you pull on it, you have the ground to press against, and since you can clearly lift more than 120lbs, you're able to apply more than 120 lbs at what I would assume is the far end of the wrench, thus you are able to apply more rotational force
Of course it is going to work better pulling the wrench counter clockwise instead of pushing it clockwise to loosen lugnuts.......
Originally Posted By: Chris142
Eat some cheezeburgers! Geez!
I have a steady diet of cheeseburgers.
When I worked as a summer student in a gas plant I was told to never push on a wrench. I assume it's a safety thing. When the bolt breaks loose, or slips off the nut, you could fall forward into "who knows what". Good thing pulling is stronger than pushing. But to move a heavy load on a trolley for example, you should always push, not pull. Pushing is easier on the back.
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