1. Field of the Invention
This invention relates to a continuously lockable adjusting device for use on pivotably mounted parts and vertically adjustable equipment, such as on slats and seats of vertically adjustable chairs.
2. Description of the Related Art
In the case of continuously lockable adjusting devices of the general type as of the present invention, it is known for a piston to be positioned, axially movably, via a piston rod, in a cylindrical housing filled with a fluid, with the piston subdividing the housing into two pressure chambers. A locking valve, present in the housing, allows the continuous locking of the adjusting device, such that, in the closed state, the locking valve prevents an exchange of the fluid between the two pressure chambers. To open the locking valve, a closing member of the locking valve is actuated by a transmission disc fastened to a trigger tappet. The trigger tappet, in turn, is positioned axially displaceably or pivotably in a guide bush with a bearing seat on which a transmission disc is supported, when the adjusting device is in a locked state. The bearing seat also prevents the trigger tappet and the transmission disc from coming loose from the housing. Because of certain tolerances of fit of the various components, due to machining of parts and their subsequent assembly, an inexact fit sometimes occurs between the trigger tappet with its transmission disc, and the closing member of the locking valve, resulting in the occurrence of some play or a gap between those parts, with the consequence that the transmission disc does not sit directly on the closing member. In the event of an actuation of the trigger tappet, the play first has to be overcome before the transmission disc impinges onto the closing member. This further reduces the extent of trigger-tappet travel, which, in any case, is only slight to begin with, which is available to actuate the closing member to open the locking valve. When the closing member is actuated as a result of a tilting movement of the transmission disc, the existence of any play between the closing member and the transmission disc has the effect that the locking valve does not open correctly and the adjusting device does not operate properly.