CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Mechanical non-car related question: How does the weight adjustment gadget

How does that weight adjustment gadget on Cybex weight machines work. There’s the standard stack of weights, and you put a rod into that stack at the weight point you want to lift, and when you lift it lifts all the plates above that point. But there’s a mysterious knob at the top that allows you to add 5, 10, or 15 pounds just by twisting the knob. I’ve looked from every direction I could figure, and from what I can tell you still lift the same plates irrespective of the knob setting. There’s no missing weights left behind.

Sorry if this is too off topic, but I think some of the mechanical experts here might know off hand.

I don’t know what you are talking about but the only way would be to either at tension, as in spring expansion or resistance, or changing the leverage. Otherwise its a ruse.

I think you are right, it probably isn’t actually adding weight, it is adding a friction force to resist motion. So when you move your arms to lift the weight it feels like it is heavier, but when you hold your arms steady it would feel the same weight irrespective of how you set the knob. If I had a 30 pound fish weigh-er I could bring that into the gym and test your theory. But I don’t fish. Sigh.

Suitcase scale if you travel but don’t fish.

Sorry to put the screws to this discussion, but I have the heavy responsibility of saying this has nothing to do with vehicles or driving. :slight_smile:

2 Likes