Valve actuation system comprising a discrete lost motion device

A valve actuation system for actuating at least one engine valve in an internal combustion engine, the system comprising:

• a first arm operatively connected to a valve actuation motion source to receive valve actuation motions therefrom and having a first arm contact surface;
• a second arm operatively connected to the at least one engine valve to impart valve actuation motions thereto and having a second arm contact surface;
• and
• a discrete lost motion device that includes a locking mechanism and further comprising:
• a housing having a housing contact surface and a housing bore extending longitudinally into the housing from a first end of the housing;
• and
• a plunger disposed in the housing bore through the first end of the housing, the plunger controllable between a first state in which the plunger is rigidly maintained relative to the housing by the locking mechanism and a second state in which the plunger is permitted to reciprocate relative to the housing in response to the valve actuation motions, the plunger further comprising an end having a plunger contact surface where the end of the plunger comprises a lost motion hydraulic passage configure to receive hydraulic fluid,
• wherein the housing contact surface is configured to engage one of the first arm contact surface or the second arm contact surface, and the plunger contact surface is configured to engage another of the first arm contact surface and the second arm contact surface,
• wherein the first arm contact surface, the second arm contact surface, the housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first arm and the second arm,
• and wherein either the first arm or the second arm comprises a hydraulic supply passage configured to register with the lost motion hydraulic passage and thereby receive the hydraulic fluid used to control the locking mechanism.