Model Railway Forum banner


952 Views 1 Reply 2 Participants Last post by  alastairq
as a novice to model railways, could somebody please explain the difference between the types of motors for locos, i see some have 5 pole skew motors and others have Type 7 motors. Thank you. John C - regards to all from Australia
See less See more
1 - 2 of 2 Posts
since no-one has had a bash at answering this, I will have a go..[perhaps they are all too busy garnering information first?)

here goes.......taking motors on their own, in early days...long, long ago....motors were usually what are known as ''open frame'', a magnet at one end, an open frame and a bearing plate at 'tuther end..with the armature down the middle, open brushes the old triang X04, XT60, Romford, etc.....and variations on the theme, usualy shape, like the old Athearn motors.
These often had 3 poles, ie 3 segments.....very tough, pulled loads of amps....and would knock holes in house walls if unattended.....buffer stops needed to be just that!!
they worked well for usual engine speeds, but suffered at low speeds from a 'cogging' effect...loads of torque, though.

To improve low speed operation, we got 5 pole motors.....K's, etc...which had 45 segments so the cogging effect was reduced....still open frame jobs...but some were quite small in dimensions.

In search of smoother running, along came the likes of the 'can' motors...Sagami, Mabuchi, Mashima, etc.....these were shaped a bit like a tin can, but were very well made, precision jobs in comparison with a lot of what came earlier...which motors, although well made, used technology akin to shipyard rivetting in comparison.

we also saw the advent of the ''coreless' motor..I think Canon were amongst the first...motors such as found in recorders, etc which needed to perform ultra smoothly........I think Portescap are in this ilk?
Thes were precision instruments rather than mass produced motors, ad prices reflected this....both can and coreless motors used a lot less current as well...wiring ceased to consist of 1 inch thick busbar!
The 'coreless' motor was constructed rather differently to the conventional motor, ..being sort of inside out!.......

'skew' wound motors have their windings (the coils of wire) skewed away from the linear position..again as an attempt to smooth out the 'coggy' effect......I suspect to achieve the result with minimal cost to make?

So far I have endeavoured to cover the conventional motor...which is essentially a separate item from the rest of the loco.
because good old Hornby Dublo had the Ringfield motor, which was sort-of 'flat' in profile...and we also have the pancake motors..usually used in motor bogies, as typified by older Lima diesels....these motors actually rotated in line with the wheels...the others rotate principally at 90 degrees to the wheels....I think the idea was firstly they were cheap to make..and also, since the armature is short, yet wide in diameter, there may have been an idea of a flywheel effect?

Today's proprietary locos have motors almost built into the chassis as a unit....or so it seems.

certainly it seems harder to effect a simple power upgrade with a change of motor make? [not that it is such a necessity these days?]

( I have upgraded cheapo Mehano US diesels with Mashima an example)

As I see things, today for someone wanting to fit a motor [maybe to a kit], the top of the tree seem to be the Portescap, or coreless motors....followed by Sagami and Mashima cans..(they do make open frame motors too)....

all very confusing, isn't it?
See less See more
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.