| 摘要 |
1,221,184. Current collection installations for vehicles. BRITISH RAILWAYS BOARD. 31 Jan., 1969 [3 Nov., 1967], No. 50132/67. Heading B7L. [Also in Division G3] The contact head 4 of a pantograph installation is maintained in electrical contact with an overhead conductor wire 5 by a servo-system which includes a slug member 8 whose inertia is used to vary the pressure of the fluid acting in a cylinder 2 on a piston 3 which supports the contact head 4 in such a manner that the pressure includes a component which is proportional to the vertical acceleration of the contact head but which is in the opposite sense thereto. In an embodiment, Fig. 1, the slug 8 is connected to the rod 13 of a control valve 10 which controls flow of fluid from a fluid pressure source to the cylinder 2, and a negative feedback of pressure is applied to the rod 13 by a bellows or piston 14 so that the net thrust of the piston is proportional to the force applied to the rod 13 by the slug. A constant force is applied to the valve 10 by a spring and hence the head is urged upwards; alternatively the force may be varied by arranging a tiltable transverse bar to engage the cable and to respond to the zig-zag arrangement of the cable to control the valve 10 so that the upward force on the head 4 is smaller at midspan that at the span ends. In a modification, Fig. 3, the control valve 10 is combined with the piston 3 within the cylinder 2. Pressure fluid flows continuously through holes 6 in the piston 3 and is variably throttled by a slug 8 acted on by a spring 7 above the piston which slug is displaceable from an equilibrium position. To reduce the excess forces which occur when the wire is accelerated towards the vehicle, additional springs are provided to urge the head downwards; alternatively the fluid forces act downwards and springs are provided to give upward force on the head. Damping is provided by a projection on the piston 3 engaging a recess in the slug 8. In another embodiment, the spring 7 acts between the slug 8 and the end of a rod attached to the piston. The height of the frame may be varied by springs between the head and frame in parallel with the servo-system; alternatively, slowacting fluid pressure operation of the frame may be employed. |
