A positive displacement pump for pumping a fluid mastic comprises a plurality of cylinders each having a piston arranged for reciprocal motion within the cylinder. Movement of the piston in a first direction draws the fluid into the cylinder and movement in a second, opposite direction pumps the fluid out of the cylinder. A variable speed electric motor is drivingly coupled to a cam arrangement providing a reciprocating drive to the pistons. The cam arrangement comprises cams shaped and arranged to drive each piston in the first direction over less than half of a rotational cycle and to drive each piston in the second direction over the remainder of the rotational cycle. The cams are arranged to drive the pistons out of phase with one another.

A positive displacement pump for pumping a fluid mastic comprises a plurality of cylinders each having a piston arranged for reciprocal motion within the cylinder. Movement of the piston in a first direction draws the fluid into the cylinder and movement in a second, opposite direction pumps the fluid out of the cylinder. A variable speed electric motor is drivingly coupled to a cam arrangement providing a reciprocating drive to the pistons. The cam arrangement comprises cams shaped and arranged to drive each piston in the first direction over less than half of a rotational cycle and to drive each piston in the second direction over the remainder of the rotational cycle. The cams are arranged to drive the pistons out of phase with one another.

A positive displacement pump for pumping a fluid mastic comprises a plurality of cylinders each having a piston arranged for reciprocal motion within the cylinder. Movement of the piston in a first direction draws the fluid into the cylinder and movement in a second, opposite direction pumps the fluid out of the cylinder. A variable speed electric motor is drivingly coupled to a cam arrangement providing a reciprocating drive to the pistons. The cam arrangement comprises cams shaped and arranged to drive each piston in the first direction over less than half of a rotational cycle and to drive each piston in the second direction over the remainder of the rotational cycle. The cams are arranged to drive the pistons out of phase with one another.

A pump supplying an application system of a liquid covering product including a motor actuating at least two pistons, a drum rotated by the motor, the drum including an outer cylindrical surface having a cam profile, each piston being secured to a rod on which a roller is fastened rolling over the cam profile such that the roller connected to each piston via one of the rods is translated along the translation axis of the corresponding piston under the action of the rotation of the drum, each roller being in contact with the cam profile in an angularly offset position relative to the other rollers such that one of the pistons is moving when the other piston reaches an inversion point of its movement direction, and the pump including compensating means suitable for accelerating one of the pistons when another piston reaches an inversion point of its movement direction.