A double acting synchronizer includes cone clutch friction surfaces and jaw clutch teeth for frictionally synchronizing and positively connecting gears to a shaft, and a plurality of integrated self-energizingpre-energizingblocker assemblies. The retaining groove has an annular projection formed at its axial opening edge for inhibiting the disengagement of the Belleville spring from the retaining groove. The first linkage element is configured to connect the head component to a body component and is able to switch between a first state in which it is relatively flexible and a second state in which it is relatively rigid. The solid core has a deformation, when compressed under a final load of 130 kgf from an initial load of 10 kgf, of from 2. A linear motor causes the drive slider to reciplocate along the inclined guide surface of the swash plate through a larger stroke. Each of the connectors includes a printed circuit board, a plurality of pairs of contacts on the PCB, a plurality of pads disposed at edge portions of the PCB for compensating crosstalk, and a plurality of connecting parts for connecting electrically the pads to the pairs of contacts.