Transmission brake disengagement switch and method of operation

摘要

Controls for a transmission brake include a switch that employs resistance to motion of an axially movable plunger in order to provide tactile feedback to the operator as to the current position of the plunger, thus reflecting a particular state of the switch. In a fully depressed position of the plunger, the transmission brake is on. Shortly before this position is reached, resistance is encountered at an intermediate position at which the transmission brake is already engaged, thereby giving the user of the option of depressing the plunger further in order to provide a longer travel time of plunger back to its normal spring-biased position in which the brake is disengaged. Some embodiments activate other brake control components at partially depressed plunger positions preceding the intermediate position, whereby controlled creeping of the vehicle can be accomplished before the transmission brake is returned to a continuously engaged state.

主权项

1. A transmission brake control switch comprising:
a switch device operable to open and close a conductive path between connection points at which the switch device is connectable in a control circuit of a transmission brake in a manner such that opening and closing of the conductive path switches the transmission brake between on and off states, the switch device comprising a plunger supported for movement along an axis thereof between a normal position into which it is biased and a depressed position in which the transmission brake is in the on state; and a resistance mechanism operable to impede movement of the movement of the plunger toward the depressed position from the normal position upon reaching an intermediate position between the depressed and normal positions; wherein the plunger is arranged to put the conductive path of the switch device into a same one of an open or closed state at the intermediate and depressed positions, and put the conductive path of the switch device into the other of the open or closed state at the normal position.