The rare Pultra Radius Grinder Model 18C5 produced during and just after WW2. It was fitted with a live workhead and a hydraulically operated wheelhead thus allowing a rapid approach and withdrawal of the wheel. The workhead (to the left in the picture) was mounted on a swivelling slide and both it and the wheelhead were adjustable by screws fitted with large micrometer dials. Both workhead and wheel head had independent motors - 1,400 r.p.m. on the former and 5,600 on the latter--with each, to ensure the correct, very high speeds needed for the grinding of tiny diameters, revolving in opposite directions.
Four models were produced, the Mk. 1, Mk. 2, Mk. 3 and Mk. 4, though they differed only in the capacity of the workhead spindle bore - 10 mm for the Mk. 1 and Mk. 2 and 20 mm for the other two - and the fitting of hand or lever-feed drawbars.