1,155,652. Machine tool details. WHEELABRATOR CORP. (BALCRANK DIVISION). 16 June, 1966 [24 June, 1965], No. 27016/66. Headings B3C and B3T. [Also in Division F1] Coolant which is supplied to a workpiece during machining has its pressure varied. The work 18, Fig. 1, is clamped in a drill jig 17, carried on the table 13 of a drilling machine having a vertically movable tool head 12, and coolant is supplied to the work by a portable pumping unit 10 through a conduit 30, and a bore in the drill 15. Unit 10 comprises a base 20, mounted on castors 22, hose retaining brackets 23, and a reciprocating pump assembly 25, which is mounted on the top of, or within, base 20, and includes an air motor 26 and a pump 27, Fig. 3. The motor comprises a cylinder 53, Fig. 3, and a piston 54 slidable therein, and connected to a valve assembly 48 through passages 86-89. A piston-rod 76 connects piston 54 of motor 26, with a piston 150 of pump 27. In operation, air is supplied to the pump unit by a conduit 28, Fig. 1, through a regulator 32, a solenoid controlled valve 32, pump inlet, and inlet port 85, and the lower end of pump cylinder 151 is connected to a source of coolant by a hose 29. The coolant is sucked in through a ball valve 168 on the upstroke of the pistons 54, 150, and passes through holes 176 in piston 150 on the down-stroke. On the next stroke the coolant is forced out through a tube 180, and thence to a rotary union 24 via conduit 30. When the drill is used on a lathe, the coolant supply tube (44), Fig. 2 (not shown), is mounted in a turret 46. In a modification, the pumping unit comprises a constant pressure rotary vane pump 200, Fig. 4, driven by an electric motor 204, a solenoid valve 206, and an accumulator 207, the solenoid 210 being actuated by a switch 211 controlled by a rotary cam 215 so as to produce pulses in the coolant.