Abstract: A valve train for use in an engine is provided. The valve train includes a rocker arm assembly having a valve side arm and a cam side arm. A valve is coupled to the engine and is in contact with the valve side arm. A pushrod is reciprocatable by a camshaft and is in contact with the cam side arm. An overload feature is located on at least one of the rocker arm assembly or the pushrod. The overload feature has a reduced cross-sectional area calibrated to activate at a predefined load.

Abstract: An oil lubrication and control system, for an engine having cylinder deactivation switching lifters operated at the pressure of the full oil system, is provided with an auxiliary pressure relief valve which opens to control maximum oil pressure in the system whenever the engine speed and temperature conditions lie beyond the ability of the oil pump pressure control unit to maintain the maximum pressure limit. Addition of the auxiliary pressure relief valve allows extended operation of the switching lifters, which are limited by their construction to operation below a prescribed pressure limit. In a preferred embodiment, the auxiliary pressure relief valve is mounted in the engine crankcase in a bore connected directly with the main oil gallery to provide mounting and actuation of the auxiliary pressure relief valve with a minimum of modifications to the engine oil system design.

Abstract: An engine has switching valve actuators with positive valve lash for actuating or deactivating valves of deactivation cylinders and conventional valve actuators with negligible valve lash for actuating valves of conventional cylinders. Cams for the deactivation cylinders have increased opening and closing ramps relative to cams of the conventional cylinders. This can lead to poor combustion quality at idle and light loads and result in perceived engine roughness by an operator. To compensate for this, timing of exhaust cams of the deactivation cylinders is advanced relative to those of the conventional cylinders to reduce valve overlap of the deactivation cylinders to sufficiently near that of the conventional cylinders to provide stable combustion at idle in both conventional and deactivation cylinders with nearly equivalent power operation of all the cylinders.