Question about double drive diffs

Buckstones:

Franglais:

Juddian:
Yeah, i’m quite happy with the concept of the diff working, 100% drive in = 100% out whatever the percentages either side right up to 100% one out side and 0% the other, i’d always thought that to be honest.
I’d completely forgotten a double drive having a mid diff though, so i envisaged NMM’s lorry going down the road with 2 wheels driving at say 100rpm, one wheel stationary locked up and its opposite chum trying to spin at 200rpm, as said i’d forgotten that the mid diff would do its job.

The 25% speedo error hand grenade you lobbed in without so much as a by your leave has me completely flummoxed mind :laughing:

Presumably you’re thinking of that centre diff apportioning more drive to the two wheels driving previously at 100rpm now with drive apportioned equally between three instead of 4 they would all now be turning at 133.3 rpm, so would the speedo error not be 33.3% ? cor this has got complicated.

:smiling_imp:

I think youre right about the number of turns going to each wheel. So if our speedo reads 10mph were actually doing 13.3mph.
You`re more awake than me.

:smiley:

I wish I still had my Meccano set, then I could build a double drive with three diffs and find out definitely what would happen. I’m inclined to agree with Juddian and Franglais as above. However, with no diff between axles I think the unlocked wheel would try to turn twice speed.

Would you have used 30t Bevels, or small Contrates with 25t Pinions? :wink: :laughing: