Brake control for rotary electric tools
OwnerSvend Nymanninventor
Life of this patent
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Abstract
A brake control for rotary electric tools, particularly hand tools, comprises a pair of spring biased brake shoes positioned about the periphery of the armature of an electric motor which drives the electric tool. The brake shoes are normally spring biased into engagement with a brake drum coupled to the armature, but upon actuation of the motor a cam element moves the brake shoes back from the drum permitting the motor to operate the tool. The cam element is actuated by a solenoid preferably located in the handle of the tool and operated by the trigger mechanism. When pressure is released on the trigger, the solenoid actuates the cam through a suitable linkage causing the brake shoes to engage the brake drum on the armature thereby immediately stopping the tool and eliminating possible safety problems.
Claims6
In a rotary tool having a motor with a rotating armature and a brake drum mounted thereabout, a brake control device comprising:
- a pair of curved brake shoes pivotably mounted at one end about the brake drum and each brake shoe having a projecting portion extending outwardly from the armature and in a substantially parallel spaced relation,
- spring means normally biasing the brake shoes into engagement with the brake drum, said means comprising a separate leaf spring engaging each brake spring,
- a cam element mounted between the projecting portions of the break shoes,
- a solenoid fixedly mounted within the tool,
- a linkage connected at one end to the solenoid and connected at the other end to an end portion of the cam element, and
- means for activating the solenoid and the motor wherein the solenoid actuates the cam element to cam the projecting portions of the brake shoes outwardly against the bias of the spring means thereby releasing the brake drum and associated armature and wherein the armature is immediately halted when the solenoid is deactivated by camming the brake shoes into engagment with the brake drum under urging of the spring means.
Dependencies are inferred from the claim text.