# Formula relating angular displacement and tension.

1. May 26, 2014

### rambharath94

Hello guys,

Iam doing a project to find the tension of timing belt using a dial gauge indicator,but i can't find a formula relating the displacement of the pointer and the tension (eg: 5 deg of dislplacement of pointer = 10 units of tension).Please help me...

2. May 28, 2014

### CWatters

You also need to know the force that causes the displacement and the distance between the contact points on the two pulleys. Then draw a force diagram (triangle). The belt isn't accelerating so the vector forces sum to zero.

3. May 28, 2014

### rambharath94

Actually there are no 2 pulleys present here ,there is a plunger and gear (rack and pinion mechanism) as the plunger moves up the gear starts to rotate giving the value of tension,Now how do i need to apply your formula for this?

4. May 29, 2014

### CWatters

The normal method for measuring the static tension in a timing belt is to apply a known force, measure the deflection and apply some trigonometry...or buy a device that does it all for you.

Image from here..
http://www.pfeiferindustries.com/installation/timing-belt-tensioning.html

That's not applicable to a rigid rack and pinion so you will have to tell us more about the system and what exactly you are trying to measure. For example if there is nothing stopping the gear rotating I don't see there will be any tension in the rack.

Got a photo or drawing?

5. May 29, 2014

### CWatters

Are you talking about the system you are measuring or the measuring device?

I have a feeling you are talking about the measuring device and I was talking about the system. My guess is the device you have measures tension and displacement is that correct?