PMDC electric motor with a magnet spacer

DETAILED DESCRIPTION OF THE EMBODIMENTS The casing 1 of the PMDC motor shown in FIG.
1 has a closed end 11 and an open end 13 which is closed by an insulating end cap 14 of molded plastics material.
The rotor 30 has a shalt 31 which is journalled in bearings 32 and 33 mounted, respectively, in the closed end 11 of the casing and in the end cap 14.
Two sintered arcuate magnets 4 and 5 are symmetrically disposed within the casing 1 on opposite sides of a plane of symmetry 3 containing the longitudinal axis 2 of the casing 1, as shown in FIG.
4.
A mild steel insert 9 extending transversely across the plane of symmetry 3 engages longitudinally extending free edges 6 and 7 of the magnets 4 and 5 so as to locate the magnets 4 and 5 angularly within the casing 1.
A resiliently deformable "U"-shaped spacer 10 which, together with the insert 9, forms a spacer unit which engages two further longitudinally extending free edges 28 and 29 of the magnets 4 and 5, to hold the magnets 4 and 5 securely in position.
As shown in FIG.
2, the insert 9 has two oppositely directed lateral extensions 12 which are each disposed between and in contact with one of the magnets 4 and 5 and the closed end 11 of the casing 1 to thereby locate the magnets 4 and 5 longitudinally within the casing 1.
As shown in FIGS.
1 and 3, brushes 34 are carried by brush assemblies 17 and 18 for engaging a commutator 35 mounted on the shalt 31.
Each brush assembly 17 and 18 has a terminal extension 36 which projects through a slot in the end cap 14.
As shown in FIG.
2, the rigid insert 9 is provided with a first locating member in the form of a longitudinal extension 16.
This extension engages with complementary second locating member formed in the molded plastic end cap 14 to angularly align the end cap with respect to the casing, which in turn ensures the desired alignment of the brushes with the magnets.
The second locating member comprises a recess 15 which accommodates a resilient tab 19 formed on the brush assembly 17 for contacting the extension 16