A device for the linear drive of a pumping member in a soap-type dispenser includes a crank mechanism with a crank disc and a push rod transmitting a linear movement to a piston rod. Disengageable coupling members are located between the push rod and the piston rod to disengage the piston rod when an...http://www.google.de/patents/US6568561?utm_source=gb-gplus-sharePatent US6568561 - Drive mechanism for a soap or foam dispenser
