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# Force/Load at solid height on Progressive Spring

## Force/Load at solid height on Progressive Spring

(OP)
Hello Everyone,

I am trying to figure out the formula for Force at Block Height for a Progressive Spring.

I have been searching for the formula but no luck :( Does any know, Please help. Thanks

### RE: Force/Load at solid height on Progressive Spring

In a progressive spring, the coils are all different, so you have to evaluate each coil by itself, more or less.
For each, you calculate the force that it takes to bring that particular coil to its solid height.
For the specific answer you seek, you only need to calculate the force at coilbind for the last coil to compress, usually the smallest. When that coil is almost closed, all the other coils are already closed, and basically just acting as shims.

Mike Halloran
Pembroke Pines, FL, USA

### RE: Force/Load at solid height on Progressive Spring

Basically you need the force-displacement graph of the spring. If it is progressive, is it linearly progressive or exponentially progressive? Two springs in series will be bi-linear. Bell cranks can be set up to make it a sine function. What is you spring configuration?

### RE: Force/Load at solid height on Progressive Spring

There are more than one option for progressive spring. One option is a constant diameter coil spring with non constant pitch between the coils (progressive increasing pitch between the coils). Second option is a conical spring with constant pitch between coils. The analysis is different for each case. Basically, the process is to gradually increase the load until the two adjacent coils come to touch thereby, reducing the number of active coils of the spring (resulting in an increased spring rate). Then to continue until the next two coils touch each and so on until all coils comes to solid. For the first type of spring the two coils with the smallest pitch will come to touch. For the second (conical spring) the largest coil will touch the coil adjacent to it first.

### RE: Force/Load at solid height on Progressive Spring

When they sell progressive rate springs, how do they "rate" them, short of including a force-deflection diagram?

### RE: Force/Load at solid height on Progressive Spring

Progressive springs are custom parts.
A force-length diagram or complete geometry and material specs would ordinarily be provided or specified.

Mike Halloran
Pembroke Pines, FL, USA

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