PUMP AND DRIVE ASSEMBLIES

摘要

IMPROVEMENTS IN AND RELATING TO PUMP AND DRIVE ASSEMBLIES A pump assembly for use e.g. in analysis apparatus of the type described in U.S. Patent No. 3923463 comprises a cylinder and piston slidable in the cylinder and defining therewith a pump chamber. The chamber is defined between opposed corresponding conical surfaces of the end wall of the cylinder and a face of the piston and communicates with a passage opening into the chamber at the apex of the cone in the end wall. The end wall of the cylinder is provided by an end member separate from the cylindrical part of the cylinder and may be integral with the movable member of a valve assembly for connecting the passage to a selected one of a plurality of inlet/outlet passages. The drive for sample containers used in the apparatus of the above U.S. Patent may comprise a drive assembly comprising two motors each connected to drive a respective first bevel gear, which gears are coaxial and mesh with a freely rotatably mounted second bevel gear arranged with its axis perpendicular to the axis of the first gears and coupled to an annular member coaxial with the first gears, and means for preventing rotation of the respective first gears such that with one first gear stationary and the other first gear being rotated, the annular member will rotate in one direction and at a speed related to the speed of the motor driving the other first gear and with the other first gear stationary and the one first gear driven the annular member will be rotated in the opposite direction and at a speed related to the speed of the motor driving the one first gear.