Abstract: An engine retarding apparatus and method include an exhaust restrictor which raises exhaust pressure in the engine high enough to cause exhaust valves to float near the beginning of each compression stroke. There is an exhaust valve blocking device which blocks closing of each exhaust valve until at least near the end of each compression stroke. In one embodiment the exhaust restrictor is an engine brake and the exhaust valve blocking device includes an hydraulic actuator controlled by a solenoid valve. There is also provided an improved exhaust brake which provides a braking effect from compression strokes as well as exhaust strokes of the pistons.

Abstract: An exhaust brake for an internal combustion engine has a valve body with an exhaust gas conduit therethrough. The conduit has a center, an upstream portion and a downstream portion. The upstream portion is smaller in cross-section than the downstream portion. There is a butterfly valve member in the conduit of the valve body between the upstream portion and the downstream portion. The valve member has a cross-section and is positioned to closely fit the upstream portion when the valve member is closed. The valve member has a center and is pivotally mounted on a pivot which is offset with respect to the center of the conduit and offset from the valve member, whereby gas pressure in the upstream portion of the conduit acting against the valve member can rotate the valve member about the pivot.

Abstract: A pressure release brake for an internal combustion engine includes a master hydraulic actuator and a slave hydraulic actuator. The slave hydraulic actuator is operatively connected to the exhaust valve opening mechanism of one exhaust valve. The master hydraulic actuator is movable by an engine component to increase hydraulic pressure which moves the slave hydraulic actuator and opens the one exhaust valve near top dead center of compression strokes when the brake is operational. There is a lash adjusting mechanism for the slave hydraulic actuator. The lash adjusting mechanism includes a device for adjusting hydraulic pressure acting on the slave hydraulic actuator during exhaust strokes and thereby lash between the slave hydraulic actuator and the exhaust valve opening mechanism.