Single Rail Gearboxes

[Mad Mart]

Having rebuilt an 1850 and currently in the middle of rebuilding a 1500 single rail gearbox, it has come to my attention that the 1500 does not have the three laygear springs (137532) installed. It could be that they were omitted on a previous rebuild but it could also be that they are not necessarily required? What do they do? They seem to apply some pressure to the layshaft thrust bearing and thus the laygear assembly.

[cliftyhanger]

I am no expert, but a good friend has built many gearboxes.
I think the springs are an anti-rattle mechanism, but can increase wear. I have a feeling they were dropped at some point, either that or reconditioners leave them out to increase life.
All a bit hazy, I try to pay attention but it has a very short span thesedays.

[yorkshire_spam]

Just to confuse things... my 1979 Spitfire 1500 single rail box HAS the springs, as does the OD gearbox (unknown year) that I acquired to swap in.