The Otto Muller SR23 and SR30 "Rapid Radial Arm" drilling machines were not intended for the usual heavy-duty work associated with this type, but as machines (like the Oerlikon UB2) that could be adapted to a wide variety of drilling operations in both the toolroom and production shop.  While the Oerlikon was versatile, it was not a "Rapid", that expression refering to the ease of moving the drill bit quickly from hole to hole, this facility being provided by a 'vertical handle' on the left-hand face of the head. By pulling or pushing the handle the head - under hydraulic drive - would move smoothly in and out; raising and lowering the handle caused the head to rise and sink while twisting the handle enabled the spindle to be rotated in either direction. The makers claimed that "The little finger will move the drilling head" and "One single hand controls all movements of the machine". A button, to the right of the handle engaged a hydraulically-operated lock.
The SR23 was, in particular, highly versatile and comprised a vertical column, able to be rotated through 360°, that carried a long ram in the form of an I-section girder to which was fitted a motorised head. Apart from special-order models, the heads had only a quick-action down-feed by lever, there being no provision for a fine feed under the control of a handwheel.
The machine could be supplied on eight different stands and even suspended from a girder to give a clear working space below. Stands could be supplied as a simple, short affair with no table that allowed work to be brought up to it supported in other ways; with a single table; with a table at the front and back - with one able to be separated and carried on an independent plinth; an extra tall stand without a table but with one or more faces of the stand machined with  T-slots;  a stand with a T-slotted table at one side and a plain at the other; a table with a T-slotted table at one side and an angle plate at the other that carried a vertically disposed rotary table - and a stand designed to 'take the machine to the job' where the base had built-in rollers and, for extra stability, a widened, triangular-form foot fitted with levelling screws and a built-in spirit level.
The makers offered to make any alterations or provide special facilitates to a customer's order and would make tables of any desired design and size. They even manufactured a special head, intended for drilling glass, stone and rubber, with infinitely variable speed drive by expanding and contracting pulleys controlled by a rear-placed handwheel. The spindle, in stainless steel, was bored through to allow a flow of coolant..