Braking system with non-spring parking brake actuator

摘要

A braking system is provided that enables application and release of a parking brake with fluid control and that also maintains application of the brake during a loss of fluid pressure—all without using springs and using only a single fluid control conduit. The brake actuator for the system includes a housing defining service and parking chambers. A pushrod in the parking chamber is configured for movement with a diaphragm in the chamber. The parking brake is applied by introducing fluid on one side of the diaphragm. A clutch surrounds the pushrod and includes a tooth configured to engage corresponding teeth on the pushrod to hold the position of the pushrod even during a loss of fluid pressure. The clutch is rotated under fluid control to move the clutch tooth into and out of alignment with the teeth on the pushrod to hold and release the parking brake.

主权项

1. A brake actuator, comprising:
a housing defining a service brake chamber and a parking brake chamber; a service diaphragm disposed within said service brake chamber; a service pushrod disposed on a first side of said service diaphragm a parking diaphragm disposed within said parking brake chamber; a parking pushrod extending through said parking diaphragm, said parking pushrod having a first end disposed on a first side of said parking diaphragm and extending into said service brake chamber and disposed on a second side of said service diaphragm, said parking pushrod defining a first plurality of teeth; a spring disposed within said service brake chamber on said first side of said service diaphragm and biasing said service pushrod to a service release position and said parking pushrod to a parking release position; a clutch disposed about said parking pushrod and defining a clutch tooth on a radially inner surface configured for intermittent engagement with said first plurality of teeth of said parking pushrod; and a clutch actuator configured to control rotation of said clutch wherein introduction of fluid on said second side of said service diaphragm urges said service pushrod away from said service release position towards a service apply position, introduction of fluid on a second side of said parking diaphragm urges said parking pushrod away from said parking release position towards a parking apply position and said service pushrod away from said service release position towards said service apply position.