GB485296A - Improvements in or relating to brakes - Google Patents

Abstract

485,296. Eddy current brakes. LIST, H. Nov. 17, 1936, No. 31417. [Class 103 (i)] An eddy current brake for vehicles or brake test apparatus comprises a rotatable electromagnet with an air gap bounded on one or both sides by a number of poles which divide the flux across the gap into a number of streams and a sta. tionary eddy current member disposed in the gap, this member having a chamber through which cooling liquid can be circulated. The brake shown in Fig. 1 comprises a pot magnet with a casing 1c and core la provided respectively with polepieces 1d, 1e one or both of which are toothed or gapped. The magnet is driven by a shaft 4 mounted in a bearing 5 and having slip rings 7, 8 engaged by brushes 9, 10 for energizing the winding 1g. The cylindrical part of the stationary eddy current member 2 preferably of copper is disposed in the gap between the polepieces and its base is formed with a chamber 2a through which cooling fluid can be circulated. The shaft 12 of member 2 has a bearing 14 slidable within the core 1a and a bearing 15 on a bracket 16 which is adjustable on the base plate 6 to adjust the extent to which the member 2 projects into the gap between the polepieces and thus the braking action. For brake test apparatus the shaft 12 carries a lever 17 to which the weight for compensating the braking torque is attached. In Fig. 1a, the cylindrical eddy current member 2 is replaced by one 21 of disc form disposed between polepieces 1d<11>, 1e<1> of the magnet, the disc being hollow for the cooling fluid. To reduce the magnetic reluctance of the air gap between the polepieces, pieces 20 or filings or turnings of magnetic material such as iron may be distributed in the copper eddy current member.