Abstract: A piezoelectric bending transducer is described which is suitable for installation in a valve channel. It is composed of at least one ceramic layer which is metalized on both sides and has piezoelectric properties and which is polarized such that on application of a voltage it undergoes a change in length, and of at least one rigid molding which is joined to the whole surface thereof and has approximately the same surface dimensions and which on application of a voltage does not undergo an elongation or undergoes an opposite elongation. The piezoceramic layer contains an unmetallized area which has a roughness R.sub.a of less the 0.5 .mu.m and covers an orifice in the valve channel.

Abstract: In apparatus for controlling a lubricating device which is actuated by pulses of compressed air, the apparatus including a drive piston disposed in a cylinder to undergo reciprocating movement under the action of each such pulse and a control valve disposed between the source of such pulses and the lubricating device, the control valve is periodically opened to permit one such compressed air pulse to be delivered to the lubricating device only after a predetermined number of compressed air pulses have been produced, by means of a stepping mechanism which includes a reciprocating pump connected to be driven by the drive piston to supply, in response to each cycle of movement of the drive piston, a predetermined quantity of liquid, an actuating cylinder containing an actuating piston and arranged to receive each such quantity of liquid to move the piston in a unidirectional, step-wise manner so that the actuating piston advances through the cylinder in discrete steps as a series of quantities of liquid are supp