New underfloor, low friction gearboxes.

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New underfloor, low friction gearboxes.

Postby Proto87Stores » Fri Sep 02, 2016 3:11 pm


As part of the progress on the new underfloor power and trailer DMU, EMU Tram and Passenger sprung and equalized car bogies, I've designed and am now manufacturing a range of precision, ultra low profile, very low friction, floating gearboxes. While these are primarily intended for the new underfloor power bogies, they can of course separately be used in most other S4, EM and 00(P) applications, and even 4mm 3 ft gauge.


Because the gearbox uses ball bearings throughout, there is no need for the extra friction of thrust washers nor any FWD -REV slop in the drive, except for that in the gears themselves. The axle ball bearings considerably reduce the friction otherwise caused by adding extra weight to vehicles using pin-point axle bearings.

Specifically for S4 users, and other creative and skilled modellers, I will shortly offer a bare bones kit, consisting of the simple, snap together steel body and the 2 pairs of miniature ball bearings (1.5 mm and 2mm) for the gearbox shaft and wheel axle respectively. The skilled user merely provides his or her own Ultrascale 15:1 worm gear set, drive shaft and axle. A third 1.5 mm ball bearing and UJ set for the drive shaft is available separately if needed.

Andy Reichert

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Russ Elliott
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Re: New underfloor, low friction gearboxes.

Postby Russ Elliott » Sat Sep 03, 2016 11:21 am

Superb, Andy. Presumably the gear ratio is 15:1? Is the shaft pitch 4.75mm?


Re: New underfloor, low friction gearboxes.

Postby Proto87Stores » Sat Sep 03, 2016 2:29 pm

There are two versions of the box, so that the gears sets are somewhat second sourced.


1. for GSL/Ultrascale using the UK obtainable 15:1 gear set above. Inter shaft pitch I'm using is 3.76 mm

2. for NWSL, using their US available 14:1 gear set. Their Inter shaft pitch is 3.35 mm.

So both versions of the gear box are significantly lower height than the ones typically used for 3.5 mm and 4 mm scales. For size estimation, the wheel shown is 10.5 mm dia. The box in the picture is has the NWSL gear set and is 5.4 mm height above the axle centre. The GSL version is around 0.4 mm higher.


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