Theoben Rapid Forum

Has anyone else looked at swapping out the belleville washers for a heavy duty coil spring?

I found a range of heavy duty mould springs and some are seriously strong for their size.

My rationale is that the multiple belleville assembly must introduce an awful lot of inertia in comparison to a single coil spring that suffers almost zero frictional resistance to its movement.

I've tried one with my reg and it seems to be very responsive and quick to recover after a shot. The block pressure jumps back much quicker, from what I can see from a gauge attached to the blanking port underneath.

Retired engineers must be the scurge of air guns!

Sounds interesting but... belleville washers allow fine tuning of the spring rate by changing the stack or thickness of the washers

Quote from: Daztilley on April 13, 2025, 12:03:23 PMSounds interesting but... belleville washers allow fine tuning of the spring rate by changing the stack or thickness of the washers

That is a good point.
I've not tried the other springs available yet. The ones I have are colour coded so although probably not as able to be as finely tuned as a belleville stack, my early initial efforts seem promising.

I'll try the other grades a bit later and see which perform better.

I'll post my results later.

Look forward to seeing how you get on mate 👍

Belleville washers win every time.can take up less space than a spring and longer life span of keeping the memory tension.
kevG

Thanks for returning to me. That does seem to be the consensus.
I was wondering about the inter-surface friction of the many plates in comparison to a coil. It exists of course but while a spring does not suffer from that type of friction, its compression involves a rotational element as the helix of a spring expands and contracts  and so introduces an element of latency.
On the other hand, the amount of movement of the valve is really not very much so the rotational delay (or latency) is going to be very small.
I tried a heavy duty mould spring in my TTR2 this week. They can be bought with different load ratings and are graded by colour. Blue - 14mm OD with a 7mm bore 20mm long. A Yellow grade was too soft. The reg seems to be quite responsive.
Perhaps the Belleville  washers need replacing - it's only been 17 years after all!