A valve actuation system comprises a valve actuation motion source configured to provide a main valve actuation motion and an auxiliary valve actuation motion for actuating at least one engine valve via a valve actuation load path. A lost motion subtracting mechanism is arranged in a pre-rocker arm valve train component and configured, in a first default operating state, to convey at least the main valve actuation motion and configured, in a first activated state, to lose the main valve actuation motion and the auxiliary valve actuation motion. Additionally, a lost motion adding mechanism is arranged in a valve bridge and configured, in a second default operating state, to lose the auxiliary valve actuation motion and configured, in a second activated state, to convey the auxiliary valve actuation motion, wherein the lost motion adding mechanism is in series with the lost motion subtracting mechanism in the valve actuation load path.

A hydraulic tappet configured for a valve train of an internal combustion engine is provided. The tappet includes an outer housing, a socket plunger, and a hydraulic lash adjuster assembly. The socket plunger and the hydraulic lash adjuster assembly are disposed within the outer housing. The hydraulic lash adjuster assembly includes an outer casing, a piston, and a check valve assembly. The outer casing is configured with a spherical first end. The hydraulic lash adjuster assembly can include a swivel pad that engages the spherical first end. The piston is at least partially received by an opening in the outer casing. The piston and socket plunger define a first fluid chamber, while the piston and outer casing define a second fluid chamber. The check valve assembly is arranged to fluidly connect the first fluid chamber to the second fluid chamber.

An internal combustion engine defining at least one cylinder, the internal combustion engine including a first camshaft lobe, a second camshaft lobe, a valve in fluid communication with the at least one cylinder, a pivot, and a follower in contact with and operatively engages the pivot, the valve, the first camshaft lobe, and the second camshaft lobe. During use, the follower is operable in a first mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve, and a second mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve and the second camshaft lobe and the valve.

An internal combustion engine defining at least one cylinder, the internal combustion engine including a first camshaft lobe, a second camshaft lobe, a valve in fluid communication with the at least one cylinder, a pivot, and a follower in contact with and operatively engages the pivot, the valve, the first camshaft lobe, and the second camshaft lobe. During use, the follower is operable in a first mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve, and a second mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve and the second camshaft lobe and the valve.

An internal combustion engine defining at least one cylinder, the internal combustion engine including a first camshaft lobe, a second camshaft lobe, a valve in fluid communication with the at least one cylinder, a pivot, and a follower in contact with and operatively engages the pivot, the valve, the first camshaft lobe, and the second camshaft lobe. During use, the follower is operable in a first mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve, and a second mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve and the second camshaft lobe and the valve.

An internal combustion engine defining at least one cylinder, the internal combustion engine including a first camshaft lobe, a second camshaft lobe, a valve in fluid communication with the at least one cylinder, a pivot, and a follower in contact with and operatively engages the pivot, the valve, the first camshaft lobe, and the second camshaft lobe. During use, the follower is operable in a first mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve, and a second mode, in which the follower is configured to transmit motion between the first camshaft lobe and the valve and the second camshaft lobe and the valve.

An engine valve lifter assembly comprises a lifter body, a plunger assembly, and a spring. The lifter body comprises an oil control portion comprising an exterior surface, oil ports, and an interior oil chamber. A plunger interface end comprises an interior plunger chamber and a second spring seat. Selectively reciprocating plunger assembly comprises a piston end coupled to reciprocate in the oil chamber and a cam input end comprising a spring seat. A spring is biased between the spring seat and the second spring seat. The spring is configured to push the cam input end away from the plunger chamber. A sleeve is coupled around the oil control portion of the lifter body, and the sleeve is slidable between a lower position and an upper position to selectively block and unblock the oil ports.

An engine compression braking system includes a brake tappet linking an exhaust cam to at least one exhaust valve of an engine cylinder. The brake tappet is connected with a working fluid that selectively activates and deactivates a compression braking mode of operation by selectively engaging and releasing a lash assembly of the brake tappet relative to a housing of the brake tappet.

An engine compression braking system includes a brake tappet linking an exhaust cam to at least one exhaust valve of an engine cylinder. The brake tappet is connected with a working fluid that selectively activates and deactivates a compression braking mode of operation by selectively engaging and releasing a lash assembly of the brake tappet relative to a housing of the brake tappet.

Systems for valve actuation in internal combustion engines provide configurations for hydraulic lash adjusters and valve actuation valvetrain components that are particularly suitable for prevention of HLA jacking in lost motion cam environments and in valve bridge environments. In one implementation, a rocker arm may transmit motion from a lost motion cam having main event and auxiliary event lobes. Main event motion is transmitted to two engine valves through the rocker arm, a lash adjuster, lash adjuster loading component and valve bridge, which define part of a first load path. Braking motion is transmitted to one of the engine valves through an inboard valve actuator and bridge pin, which define part of a second load path. The HLA is thus disposed in a separate load path from the braking valve load and the lash adjuster loading component keeps the lash adjuster under a constant compressive force to prevent jacking.