Brake assurance module

Abstract

A brake assurance module assures braking on at least one truck. It includes a summer, a level circuit, a delay circuit, an emergency driver, a valve driver and a timer circuit. The summer sums friction and dynamic braking signals into a total braking signal. The level circuit generates a threshold signal when the total braking signal exceeds a threshold. The delay circuit generates a level signal after having received the threshold signal throughout a preset time. When the emergency driver receives an emergency signal, it conveys a detect signal. The valve driver controls contacts each in series within a control line used to energize a valve whose operation is normally controlled by the brake control system. The valve driver when activated closes the contacts thereby permitting the system to control the valves. When deactivated, the valve driver opens them thereby preventing the system from controlling the valves. The timer circuit has set, trigger and reset inputs. When the set input receives the level and zero speed signals simultaneously, the timer circuit activates the valve driver thereby placing the module in a standby mode. The timer circuit monitors the trigger input for the detect and full service signals in response to which it becomes enabled. If the reset input receives the level signal within a predetermined time after the timer circuit enables then the timer circuit resets thereby keeping the module in the standby mode. Otherwise, the timer circuit deactivates the valve driver thereby placing the module in an intervention mode.