An improved deactivation hydraulic lash adjuster wherein the prior art lost motion spring or springs formerly located within the body of the DHLA and below the pin housing are either omitted completely or are reduced in length, spring force, and/or number and are augmented hydraulically, allowing a shorter, more compact lifter body and reduced overall lifter length. The prior art lost motion spring chamber becomes a hydraulic chamber connected to a new pressurized oil supply gallery containing an accumulator in the engine. An embodiment having no lost motion spring and solely hydraulic lost motion return can be even shorter than a spring-hydraulic hybrid because the potential hydraulic pressure to be brought against the pin housing is not a function of the length of the lost motion chamber, which length is limited only by the required displacement of the pin housing.
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