Patent GB-190613450-A (GB)
Title: Improvements relating to Trolley Poles of Electric Tramcars or the like.
Inventor: COLLIE JAMES HUNTER
Filed: 1906-06-12
Granted: 1907-04-18
Abstract: 13,450. Collie, J. H. June 12. Electric railways and tramways on the overheadconductor system. Collectors.-Relates to means for automatically lowering the trolly poles of electric tramcars or the like when they leave the trolly wire, and consists in connecting the springs to the trolly pole so that, when the latter rises beyond a predetermined limit, the point of attachment is automatically moved so as to reduce the leverage of the springs sufficiently to allow the pole to descend. Fig. 2 shows the invention as adapted to a trolly pole in which the springs are placed in a vertical position. The pole is mounted on the spindle 4 and pivotally carries, by means of the pin 3, a lever 2, one end of which is bifurcated and held up by the bar 8. This lever is provided with a recess in which the rollers 5<a>, carrying the block 5<b> connected to the main spring by the link 6, can reciprocate when free. The lever 2 also carries a detent catch 9, pivoted at 10 and adapted to hold the block 5<b> normally in the position shown. When the trolly arm rises excessively, the end of the lever 9 comes against the stop 12 and releases the block 5<b>, which then moves towards the pin 4. The leverage of the spring is thus reduced sufficiently to permit the trolly arm to fall until the end of the lever 2 comes against the fixed stop 11. If the pole is depressed farther, the parts automatically move back into their normal positions. Fig. 6 shows the invention as applied to a trolly in which the springs are placed horizontally. In this form, the blocks 5<b> are carried in slots 16 in the bifurcated portion of the trolly arm and are kept in their upper position by the spring-pressed catch 9<a>. A chain 20 which passes over the pulley 22 is secured at one end to the catch and at the other end to the base 21. When the trolly pulley leaves the conductor, the movement of the pulley 22 causes the catch to release the block 5<b>, which then falls and reduces the leverage of the springs. To re-set the mechanism, the pole is depressed farther, when the interaction of rollers on the spindle 5 and the cam - surface 24 raises the blocks 5<b> into their normal position. When the variations in the height of the trolly wire are large, a dash-pot may be fitted to either of the arrangements described in place of the positive tripping-devices. In a modified form, the lever 2, Fig. 2, is fulcrumed on the main spindle 4, and its free end operates between the stops as before. Pivoted to the lever is a wheel fitted with a crank-pin to which the mainspring is connected. Normally, the pin is located diametrically opposite to and remote from the fixed end of the mainspring, the wheel being held in position by the engagement of a tooth or notch on its periphery, opposite the crank-pin, with the end of the shorter arm of the trolly pole. When the trolly pulley leaves the wire, the lever 2 descends until arrested by the lower stop. The inertia of the pole carries the shorter arm lower, thus disengaging the wheel and leaving it free to rotate. The leverage of the springs is thus reduced. To re-set the mechanism, the wheel is rotated by hand.