Latest research from the mad norwegian professor...

[narrowgauger]

Hi Ray

what the pivot on one axle will achieve is a 3-point suspension system.  This ensures that all wheels are on the rail [within reason] in the same way that a 3-legged milking stool is always stable.  this form of suspension works very well since it does not alter the coupler hight in any way and will allow the belt tension to remain [almost] constant.

the added benefit of this arrangement is that the crucial cross helical gear mesh is not in any way jeopardised by the suspension arrangement since this axle is "fixed" in its position.

By the way there is a fundamental problem with the belt drive chassis shown in this thread insofar that the axles captive in the frame, i.e. the axles cannot be removed without taking a wheel off on each axle.  Unfortunately with a neoprene belt drive it is imperative that the axles be removable from the chassis to allow belt replacement.  Depending on various factors regular belt replacement is unfortunately a fact of life.

Hope this answers your question.

have fun
Bernard

[Franck Tavernier]

@ Ray,

Pivot point is a 3 points compensation system. For locos with small number of wheels, like little gas locos like mind, springs are very often difficult to adjust and set up...

For four wheels locos, the leading axle must be in fixed bearings and it's the only possible driving axle. The rear axle is carried in bearing that are allowed a small amount of vertical movement from the axle centreline with a central pivot point to both control height and allow pivoting. Pivot point can be make with a support bar, a bolt (like my model, I used a slotted socket head bolt) or a simple rod.





The advantage of the bolt placed vertically is that the rear axle can be trimmed exactly horizontal by adjusting this bolt!

Have a look at this digest :

http://www.clag.org.uk/41-0rev.html#section1

@ Bernard,

I use 1mm dia. O-rings belt drive. The material isn't neoprene, but nitro-butene (or nitrile rubber), a high quality artificial rubber.

I agree that with my frame concept, the O-ring cannot be changed easily, and the frame side cannot be removed without taking the wheels off on each axle...however, there is no need until now, the loco has already run more 50 hours at home and on exhibition service, without problem...So, belt replacement isn't as frequent as we could imagine! And with a Puller or equivalent it's easy to take off the wheel on each axle, and I made a jig to mount the wheels on his axle and to have quickly the good back to back size wheels     

Franck