| 摘要 |
635,382. Electric motors. MATEMINE. Oct. 10, 1947, No. 27234. Convention date, Feb. 22, 1946. [Class 35] [Also in Groups XXX and XXXVII] A stop-block of the kind located at the centre of a rail track and adapted to b) elevated to the height of the wheel axles of a car or train of cars is operated by an electric motor, the rotor of the motor acting as nut on a screw threaded stem which carries the stop-block and is moved upwardly by the revolution of the rotor until it becomes locked at the end of the upward travel whereupon the rotor, in continuing its rotation, is moved longitudinally backwards and ultimately opens the circuit to stop the motor. When the motor is again switched on, for retraction of the stem and stop-block, stopping is effected by the screw-threaded stem at the end of its downward movement. A head 1 is provided with two thick side ribs 5, each formed with a vertical guiding-groove on the outside face for a movable finger 6, the two fingers being interconnected by a transverse pin 9 mounted in a slider 19, so that the ends of the pin project through vertical slots 8a into recesses in the respective fingers 6. A screwthreaded stem 18 integral with the slider 19 extends downwardly into engagement with internal screw-threads in a sleeve shaft 14 on which the rotor 13 is mounted, the lower portion of the sleeve shaft being formed with a shoulder to engage a spring 16 on a ball-thrust bearing 15. The lower ends of the screw 18 and sleeve 14 respectively bear against push rods carried by cylindrical contact heads 22, 23 located in separate bores in an insulating block 21 and serving respectively, when in the requisite positions, to close a circuit between pairs of diametrically opposed spring-pressed contacts 24 or 25 connected in relay circuits of a reversing-switch. With the fingers 6 initially in their lower position the operation of a drum controller actuates the rotor so that the screw 18 is raised to its upper position to elevate the fingers 6, and then locks, whereupon continued rotation of the rotor causes the sleeve shaft 14 to move downwardly and depress the contact head 22 to open the motor circuit. To return the fingers 6 to their retracted position the controller is operated to close the motor circuit through the contact head 23, this circuit being opened when the lower end of the screw 18 is pressed downwardly upon the pusher pin associated therewith. |
