| 摘要 |
1,179,574. Change-speed gear. CROUZET. 19 April, 1967 [27 April, 1966], No. 17865/67. Heading F2D. [Also in Division H2] An oscillating motor has a stator with at least one field coil and a polarized rotor whose amplitude of oscillation may be varied. The rotor carries a pawl having two operating portions which engage with one of two coaxial ratchet wheels which have different numbers of teeth to provide differing output speeds. The motor comprises a cup-shaped housing 1 and a wall 2 which contains a field coil 4 connected to a single phase A.C. supply through resistor R. A rotor 6, including an annular permanent magnet 6a, is mounted on a non-magnetic shaft 5 and co-operates with polepieces 3. The rotor has two diametrically opposed arms 6c, 6d which are aligned with arcuate slots in wall 2. A pair of springs are attached between pin 10 and the wall and are rated such that the mechanical resonant frequency of the moving parts is approximately equal to the supply frequency. A pawl 8 is attached to pin 7, mounted in arm 6c of the rotor, and is biased by spring 9 so that nose 8a of pawl 8 engages with ratchet wheel 12. When the amplitude of oscillation is increased by short circuiting resistor R using contact K, the end 8c<SP>1</SP> of pawl 8 is moved under stop 18 so that nose 8b of the pawl engages with ratchet wheel 13. The number of teeth 12b, 13b are different so that differing output speeds are obtained from drive pinions 12a, 13a. Pawls 14, 15 prevent reverse rotation of the ratchet wheels.
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