Aspects of the present disclosure are directed to valve clearance adjustment systems and related methods that can be used to quickly and easily establish and accurately fix a desired gap between valve stems and associated valve adjustment screws attached to rocker arms, such as may be used with intake valves, exhaust valves, and fuel-injection mechanisms, among others, within, e.g., an internal combustion engine. Various alternative implementations and related methods are provided.

In accordance with at least one aspect of this disclosure, a system can include, a moveable component configured to move between one or more positions, a biasing member operatively connected on a first side to bias the moveable component to a respective one of the one or more positions, and a preload member operatively connected to provide a force to a second side of the biasing member. An actuator can be operatively connected to move the preload member in response to a signal from a controller.

Methods and systems are provided for a valve spring retainer of a valvetrain assembly. In one example, valve spring retainer may be at least partially hollowed and include inner cavities forming channels within a material of the valve spring retainer. Air inside the inner cavities may be fluidly coupled to air surrounding the valve spring retainer through channels. A mass of the valve spring retainer may be decreased and a cost and speed of fabrication of the valve spring retainer may be reduced by additive manufacturing.

A method for setting lash on a switching rocker arm assembly includes providing a rocker arm having (i) an outer arm having a first outer side arm and a second outer side arm, the outer arm defining an opening, (ii) an inner arm disposed between the first and second outer side arms, (iii) a roller follower that selectively engages a cam, the roller follower mounted about a bearing axle that extends through the opening. A zero lash shim is inserted into a gap defined between the bearing axle and the outer arm at the opening. The rocker arm is installed into the valvetrain with the master tip cap. Lash is measured between the cam and the roller follower. The rocker arm and the master tip cap is removed. A select fit valve tip cap is installed based on the master tip cap and the measured lash.

An apparatus includes a valve and an actuator. The valve has a portion movably disposed within a valve pocket defined by a cylinder head of an engine. The valve is configured to move relative to the cylinder head a distance between a closed position and an opened position. The portion of the valve defines a flow opening that is in fluid communication with a cylinder of an engine when the valve is in the opened position. The actuator is configured to selectively vary the distance between the closed position and the opened position.

A switchable castellation assembly can include a lost motion shaft, the lost motion shaft being configured to transfer a lift profile to a valve end. A switchable castellation device can comprise a rotatable first spline bushing and a spline body, wherein the first spline bushing can be changed between a locked position and an unlocked position, and a lost motion can be obtained by sliding the lost motion shaft.

A rocker arm includes an outer arm defining a stop aperture with a stop surface; an inner arm which selectively pivots relative to the outer arm; a latching mechanism which switches the rocker arm between a coupled state in which the inner arm is prevented from pivoting relative to the outer arm in a first direction and a decoupled state in which the inner arm pivots relative to the outer arm; a lost motion spring which biases the inner arm to pivot relative to the outer arm in a second direction which is opposite from the first direction; and a stop pin fixed to the inner arm and extending into the stop aperture such that the stop pin is circumferentially surrounded by the stop surface and such that the stop pin within the stop aperture limits the extent to which the inner arm pivots relative to the outer arm.

A hydraulic valve brake for a hydraulic valve drive of an internal combustion engine is provided. The valve brake includes a housing with a housing wall and with a housing base, and includes a piston which moves axially in the housing and one end side of which, together with the housing wall and the housing base, delimits a hydraulic pressure chamber and the other end side of which actuates a gas exchange valve. The housing wall is perforated in the region of the pressure chamber by one or more overflow openings, the opening cross sections of which are controlled by a control edge, which delimits the end side at the pressure chamber side, of the piston. In this case, it is the intention for the axial distance (h) between the control edge of the piston, when the latter is fully retracted into the housing, and the housing base to be set by a spacer of predetermined thickness (d).

A lash adjuster can include a hydraulic lash assembly, a mechanical lash assembly, and a check assembly. The hydraulic lash assembly can include a body, a top plunger, a leak down plunger, and the check assembly between the body and the leak down plunger. The mechanical lash assembly can be between the top plunger and the leak down plunger. The mechanical lash assembly can include a shim abutting the top plunger, a spacer, and a spring pressing against the spacer and the shim to form a gap between the top plunger and the leak down plunger. The lash adjuster can include the spring pressing directly against the spacer and directly or indirectly against the shim.

An improved length adjustable pushrod device for disposition in an internal combustion engine between a rocker arm and a cam shaft comprises a base rod section having a hollow interior extending between an inward seat within the hollow interior and an outward opening at one end of the base rod section and an extension rod section having one end thereof insertable telescopically through the outward opening at the one end of the base rod section and into the hollow interior thereof. The base and extension rod sections define a collective length of the pushrod device when assembled. At least one shim is provided for selective disposition in the hollow interior of the base rod section between the seat thereof and the one end of the extension rod section for selectively varying the collective assembled length of the base and extension rod sections.