Abstract: A control mechanism (1) for an engine valve (29) comprising two rotatable cams (8, 10) which engage a lever (2) at two follower regions (23, 34) at different positions, the lever (2) having a zone of application (35) linked to the valve (29) whereby rocking movement of the lever (2) consequent on rotation of the cams (8, 10) causes opening and closing of the valve (29), wherein one of the two cams (8) is in constant engagement with the lever (2) and the other cam (10) is in periodic engagement with the lever (2), a gap (26) being provided between the other cam (10) and its respective follower region (23) when the other cam (10) is not in constant engagement with the lever (2), the width of the gap (26) affecting the duration of opening and closing of the valve (29) and its stroke length. Preferably, the zone of application (35) of the lever (2) is movable longitudinally along the lever (2) to thereby vary the stroke length of the valve (29).

Abstract: A mechanism to vary the lift of a valve of an internal combustion engine, the valve being operated by a cam lobe on a cam shaft. A lever is pivoted to a support rotatable about the cam shaft, the cam lobe acting on a shaped bearing area on the lever, the other side of the lever contacting the cam follower, so that by rotation of the support the timing of lift of the valve can be varied. Provision is also made for varying the degree of lift independently of the timing by means of a further lever pivoted to a sleeve rotatable about the cam shaft, the further lever contacting the first lever on one side and the cam follower on the other side. Rotation of the sleeve causes the effective lever arm of the first lever to be varied and thereby the degree of lift of the valve.

Abstract: A mechanism for varying the lift and duration of lift of the valves (1) of an internal combustion engine comprises a primary hydraulic cam follower (4) actuated by a primary cam (5), a secondary hydraulic cam follower (8) actuated by a secondary cam (7), a housing (18) for the secondary cam follower (8) adjustable about the axis of the secondary cam (7) so that the timing operation of the secondary cam follower (8) can be varied, characterized in that the bleed of hydraulic oil from the primary hydraulic cam follower (4) is controlled through the secondary cam follower (8) and thereby the rate and timing of lift of the primary cam follower (4) to thus give a variation of the time and rate of opening and duration of opening of the valves (1).