Double-ended motors required

[martin.retired]

I've recently modified a couple of IP chassis by replacing the nylon worm and gear with steel and brass parts from Cambrian.

The ratio is 20:1 rather than the original 16:1 which is OK. It looks like I've solved the worm stripping problem which was driving crazy.

I now want to improve the running by fitting flywheels. Is there a double-ended motor available which would fit into the IP gearbox housing (the older softish metal type) without too much work?

[Enginehouse]

Most double ended motors available are of a larger type and can be somewhat expensive. There are of course many commercial offerings available as spares for existing model locos, having double ended worm drive capability, but all are more powerful and none are capable of being used with an old IP gearbox casing.

Having been on the end of the dreaded IP worn worm and wheel system with two of their chassis, not to mention after very little running the plastic sides crazing around the bearing inserts, I went the complete replacement gearbox and motor route using an MFA Como motor/ gearbox unit. Plastic chassis completely replaced with ally (B&Q). Just used the original wheels and buffers. No problems since. In fact building chassis this way opens up a whole variety of drive systems enabling worm and wheel to be discarded completely.

[martin.retired]

Thanks for that Roy.

Mercifully I don't have the plastic chassis problem - mine are constructed from steel side and end plates with self-tapping screws, and have outlasted several nylon worm & gear sets

Which MFA Como motor/ gearbox did you use?

Martin

[Enginehouse]

I use mostly a 918D 30/1 ratio 12/24V, as these motor gearbox combos although rated at 12/24V will in fact work very well at lower voltages. Mating this type of motor with its output shaft being 4mm, with a pair of bevel gears p/no 918D7 to turn the drive through 90 degrees means quite simply that it's possible to drop the motor between the wheel sets. Using bevel rather than worm and wheel also means that there is no noisy reverse problem that is always evident with worm and wheel unless cross cut. When I last purchased them, a pair of bevel gears at £3.01 and the motor/gearbox/mounting assembly at £11.18 just had to be a decent option. A 4mm axle shaft will cost £1.99.

[Catweasel]

I don't know what loco you are building,but I am using the 918 motor gearbox combo in my GRS Hunslet diesel, My layout doesn't use gears as I've slung the motor across the frames between the wheels. Drive is by chain over 3 sprockets. The width of the frames is 66 mm and I've got the whole motor gearbox between them. Power to mine is a 12 volt dry cell battery filling the bonnet. It is still under construction.

[Enginehouse]

Just this morning started another brass framed chassis for the GRS Peckett kit. Using wheels and rods from Essel Engineering, off of another MFA Como 918D 30/1 motor gearbox combo slung between the wheels. Using the bevel drive the motor will happily drop in the axle space at 7.5cm. The bevel drive allowing a 180 change of drive angle where required is so very convenient. Getting all of the R/C, speed control, receiver and batteries in the loco body is going to be great fun no doubt but seems do able. Amazing how the combo allows such a nice creep away and slow acceleration.

[martin.retired]

Sorry, a long time has passed since the last few posts. I've been involved with family stuff including the arrival of our first grandchild. A lovely little girl. I suggested Lady Anne as a name but it didn't go down well!
I have a question regarding the MFA Como geared motors : Is it possible to backdrive them? I suspect that a lot of the problems associated with the worm/ gear (especially nylon) arrangement is the stresses put on the gears when overrunning occurs - ie when the train wants to go faster than the loco due to intertia. A system which backdrives would alleviate 99% of those stresses.

[Enginehouse]

Sorry, a long time has passed since the last few posts. I've been involved with family stuff including the arrival of our first grandchild. A lovely little girl. I suggested Lady Anne as a name but it didn't go down well!
I have a question regarding the MFA Como geared motors : Is it possible to backdrive them? I suspect that a lot of the problems associated with the worm/ gear (especially nylon) arrangement is the stresses put on the gears when overrunning occurs - ie when the train wants to go faster than the loco due to intertia. A system which backdrives would alleviate 99% of those stresses.

It's not possible to back drive the 918 series of motors, however there's possibly others supplied by the same company which will do the job. Best to speak to MFA direct, as they do all sorts of gearboxes -indeed they actually build some to order and are well into robotics.