Types of Armature

One of the delights of working with original Poole Graham Farish motors is their ease of access. Unlike more recent armatures (another word for electric motor), original Poole motors are not encased. This means it can be stripped down and the brushes cleaned or changed, the commutator cleaned from dirt and grease between the segments, the brush springs changed, and so on. Servicing these motors can make for a satisfying repair, should they be the cause of ill running due to lack of a service.

Before going into detail about the components of a Poole armature, let’s first look at the various armatures that were produced by Graham Farish at Poole.

Armaturetypes1

There are two elements to consider;

The design of the motor – all motors were essentially of the same design but had different gears or a flywheel on them to suit different chassis.

How many poles the motor had (3 or 5 pole) – Graham Farish originally started out manufacturing steam locomotives with 3-pole “can” motors, with the motor being completely encased within a “can” – hence their name.

Somewhere around 1982 they switched moved to 3-pole “open” motors, similar to what you see on the left. Unlike those on the left, however, they remained 3-pole until 1984, when the new 5-pole motor was released.

The 5-pole motor was to remain the motor of choice throughout the period of Poole production. It offered a better “creep” ability due to five alternations per rotation, instead of the previous three.

5-pole motors also drew less current than their 3-pole equivalents.