shortened pitman arm

[steve s]

Originally Posted by ford1

shortened pit man arms make for quicker steering, but also makes for harder steering because of lost leverage to the steering arms, and as was said, never weld one, its like a death wish if you do, to you or some one else

Originally Posted by steve s

This is totally opposite to my experience.

Originally Posted by ford1

Steve, i dont really understand why it works differnt for you, a pitman arm is like a lever, the longer it is the more leverage you get to move something, even the steering on a car, but if what you have works for you then more power to your set up, send a pic or post something about your set up that makes it work so weel, im interested

Originally Posted by Steam Engine Pete

A shortened pitman arm has the same affect as using a smaller diameter gear to drive another gear. A smaller gear would cause more torque multiplication and reduced output speed.

A shortened pitman arm will slow down the steering and increase torque which would make the steering turn easier but also slower. The benefit is reduced steering effort.

Pete

I'm struggling to stay out of physics teacher mode (it all has to do with conservation of energy), but here goes.

Saying that "a pitman arm is like a lever, the longer it is the more leverage you get to move something," is kind of ambiguous; "more leverage" can be good or bad, depending on which end of the lever you're on.

Think of trying to lift a fat man who is sitting out on the end of a teeter-totter. If the lever on your end is made longer, your job is easier; if the lever on his end is longer than yours, your job is harder. Who "has" more leverage?

In terms of the physics (I buckled), it takes the same amount of energy, or work, to lift fatso a given height in the air, no matter how long either levers are (or, even if there are no levers). However, you have options as to how much force you must apply over what distance to do that work. If you're a featherweight, you have little choice; you need him sitting on a short lever and you pushing down on a long lever. This means you have to exert your force (i.e., weight) over a larger distance to get fatso to move a smaller distance. Quibbling about who "has more leverage" could go either way and so does not really help, IMO.

Think of the ball at the end of the Pitman arm. Like lifting the fat man, it takes the same amount of work, and the ball on the end of the arm (and the drag link, etc.) has to move the same distance, to turn the front wheels a given amount, no matter the length of the Pitman arm. If the arm is shorter, it will take more turns of the steering wheel to move the ball a given horizontal distance; the longer arm will swing the ball a larger distance for the same number of steering wheel turns. The total effort (or work, or energy, if you prefer) to turn the front wheels will be the same, but it will seem easier with the shorter arm because less force is required, ALTHOUGH over a longer distance! I believe that most people would describe this as "slower" steering: a given rotation of the steering wheel turns the car wheels less. Conversely, the longer original Pitman arm would give faster steering (assuming you've got the strength to make it happen).

I hope this is clear.

While I'm rolling here, the shorter arm is only partly like power steering. True, it reduces the force needed to turn the steering wheel, but with REAL power steering the steering response would not be decreased--it's often faster than non-power steering.

Steve

[BILL WILLIAMSON]

Un-scientific example. If you're trying to lift the corner of your house with a 8 foot bar and a rock, let only 6 inches of the bar extend past the rock.
That 6 inches is the same function as the pitman arm. Chief told me that.