833,779. Pneumatic linear-dimension gauges. MICROMATIC HONE CORPORATION. March 25, 1957 [May 10, 1956], No. 9780/57. Class 106 (2). [Also in Group XXIII] A honing machine has means for gauging the diameter of the bore being honed comprising nozzles from which air escapes into the bore, the back-pressure in the air system depending on the size of bore and controlling the operation of the machine; the gauge does not enter the bore until this has been enlarged to substantially the required diameter. The gauge comprises, Figs. 1, 2 and 4, upper and lower sleeves 29, 31 secured together by an internally threaded ring 32; air supplied through a pipe 43 and connector 44 passes through passages in the sleeves to nozzles 37 in the sleeve 31. The nozzles are adjustable and the sleeve 31 carries replaceable hardened blocks 61 which are tapered to guide the sleeve 31 into the bore. The sleeve 29 surrounds a sleeve 21 mounted by a bearing 23 on the housing tool and a split ring 28 is retained in an annular recess in the sleeve 21 for co-operation with an inturned flange 27 at the top of the sleeve 29; clearance between the sleeve 21 and flange 27 permits lateral movement of the gauge. On the upward stroke of the tool, the ring 28 engages the flange 27 to raise the gauge clear of the work 38; on the downward stroke of the tool, the bottom of the sleeve 31 strikes the top of the work and is arrested, unless the bore has been honed to substantially the desired diameter, when the gauge enters the bore to an extent limited by the engagement of the ring 32 with a plate 39. The plate 39 is carried by guide bars 14 on the tool-reciprocating ram 13, so that when the tool is withdrawn from the bore it is positioned within an aperture in the plate and when the tool is lowered into the bore the plate is lowered towards the work. The plate 39 carries a rod 45 against which the connector 44 abuts to prevent rotation of the gauge with the tool; the plate 39 also carries a switch 42 operated by a finger 41 on the upper sleeve 29 each time the gauge enters the bore. In a modification, Fig. 3, the gauge surrounds a sleeve 47 having a split ring 51 co-operating with the flange 27; the sleeve 47 is mounted on a yoke 48 attached to a plate 49 secured to the end of the tool-reciprocating ram 13. Entry of the gauge into the bore, when the latter has been enlarged sufficiently to permit this, is limited by engagement of the ring 32 with a guide cylinder 53 carried by a plate 54 secured to rods 55, 55 passing through the plate 49 on the ram 13 and through a plate 57 mounted on the cylinder 58. When the tool is withdrawn from the bore by upward movement of the ram 13, the plate 49 engages rings 56, 56 on the rods 55, 55 to raise' the plate 54; the downward movement of the plate 54 when the tool is in the bore is limited by rings 59, 59 on the rods 55, 55 engaging the plate 57. A finger 41 on the gauge operates a switch 42 on the plate 54 each time the gauge enters the bore. Figs. 6 and 7 show a control arrangement for use when honing a long bore when the gauge will remain within the bore for a substantial time during each reciprocation of the tool. Air passes through filter 63, pressure regulator 66 and control valve 67 to the gauge 26 (through solenoid-actuated valve 73) and to a diaphragm 69 connected to a bar 78 co-operating with contacts 79, 81 ; when flow of air from the gauge nozzles is impeded, the contacts 79 are made. When the gauge enters the bore, finger 41 closes switch 42 to energize solenoid 82 to close contacts 83 to energize solenoid 84 to close contacts 85, 86. Contacts 86 complete a holding circuit through solenoid 84 to prevent deenergization when solenoid 82 is de-energized by finger 41 moving away from switch 42. Contacts 85 energize a solenoid 87 to open valve 73 to supply air to the gauge nozzles. Back pressure from the nozzles causes contacts 79 to be bridged, energizing a relay 88 controlling the speed of honing and the rate of feed of the honing stones. When the bore reaches the desired diameter, the reduction in back pressure causes contacts 81 to be bridged, energizing a relay 89 to open contacts 91 to de-energize the solenoids 84, 87 so as to cut off the air flow. The relay 89 may cause immediate collapse of the stones and withdrawal of the tool or may set up a run-out time adding a number of strokes without feeding the stones. A lamp 92 in circuit with contacts 85 lights while gauging is proceeding. A lamp 93 in circuit with contacts 81 lights when the bore size is correct. Fig. 8 shows a modified control arrangement for use when honing a short bore when the gauge will remain within the bore for only a short time during each reciprocation of the tool. The back pressure is applied through a booster 95 to one side of diaphragms in pressure responsive devices 97, 98; air is supplied through a regulator 101 to the other side of the diaphragms. Device 97 operates switches 103, 104 to control the speed of reciprocation of the tool and feed of the stones. Device 98 operates switches 105, 106 to terminate the operation or set up a runout period.