US2176123A - Type lever pad attachment for typewriting machines - Google Patents

Description

0a. 17, 1939. L. DENZQR 2,176,123

TYPE LEVER PAD ATTACHMENT FOR TYPEWRITING MACHINES Filed Sept. 29, 1956 Patented Oct. 17, 1939 TYPE LEVER PAD ATTACHDIENT FOB TYPEWRITING MACHINES Ludwig Denzer, Hamburg, Germany Application September 29, 1936, Serial No. 103,162 In Germany October 1, 1935 20laims.

This invention relates to a type lever pad attachment for typewriting machines consisting of a metal strap carrying a pad of elastic material. With the commonly used attachment, wherein a pad or support of asbestos, felt or the like mounted on a carrying strap is employed, it is impossible to avoid a considerable noise and to prevent the type levers fromvibrating and sinking when they recoil on to the type lever pad. However, the vibration of the type levers and the sinking into the type lever pad causes wear of the pad and of the parts belonging thereto; the function oi the key board and of the other mechanism of the machine is impaired, this having evidently a detrimental efiect on the typingspeed.

These objections are not overcome by the known pads which, for example, consist of a spiralspring wound around a. bent metal rod and provided with dowel-pins at its ends, this spring carrying through the intermediary of a flexible tube and a fabric sleeve 9. leather strip on its end facing the type levers. As such a type lever pad rests firmly on the supporting strap by meansof the screws engaging the dowel pins, the pad can- 5 not yield, but is particularly rigid so that the type levers recoil therefrom and can thus easily jam. The type levers, even after a short time, produce in the leather strip deep depressions which may even lead to the leather strip being worn right i 30 through so that the levers become damaged or their operation is impeded. Such type pads are not intended to produce and do not produce silent or quiet or quiet operation, especially as all yieldability of the spiral spring with its sleeve relatively 35 to the strap rigidly connected therewith is prevented.

It has also been proposed to employ a pad of felt, which, as in the usual known arrangements, is fixed directly in the carrier strap without any 40 clearance. In this instance registering apertures are provided in the carrier strap and in the pad for accommodating pins arranged one for each type jlever. The eifect of this known arrangement is based on the assumption that, when the type levers exceptiona-lly accurate workmanship in view of 5 the method of operation selected, andis also dis-' advantageous as the type levers will become damaged in the event of the leather strips provided over the pins being worn through, which is unavoidable.

The present invention overcomes the above 5 mentioned objections and provides a silently or quietly acting type lever pad which, in spite of the elasticity attained, neither sags nor causes a vibration or sinking of the type levers. Furthermore such a pad adapts itself to the actual varil0 able strength of the blow struck by the type lever. At the same time the pad is extremely simple to manufacture, fit and clean. The pad attachment according to the invention is characterized by the fact that the pad is separated from the carrier strap by a gap or clearance in which resilient members are arranged which enable and assist the pad to resiliently shift in its longitudinal direction.

An embodiment of the invention is illustrated by way of example in the accompanying drawing, in which:

Fig. l is a perspective View showing the pad in its carrier strap.

Fig.2 is a top plan view of the pad.

Fig. 3 is a section through the attachment taken online 3-4 of Fig. d.

Fig. 4 shows in longitudinal section a strap with pad fitted on two carrier straps.

Fig. 5 shows a supporting spring in perspective View.

A curved metal carrier strap l is fixed on supports I ll of a typewriter. As the edges 3 of the carrier strap l are bent inwardly, the penetration of dust into the strap l is prevented. The carrier strap l carries with clearance the pad 2 which comprises a flexible metal band 6, coated with a layer of elastic material, preferably rubber, having a curved cross-section and forming the pad proper. The projecting ends 5 of the band i are bent over to strengthen the metal band t which 40 has to take up the pressure exerted by the type levers in their position of rest.

Several supporting springs 6 are provided in the gap between the metal strap 6 and the metal band 6 carrying the pad 2. These springs take up the pressure exerted by the metal band ll and they consist of curved metal plates having each a hole 8 near its middle for accommodating a fixing member, such as a rivet 9, by means of which the springs 6 are rigidly fixed on the strap I. The supporting-springs 6 exert radial pressure upon the resilient metal band 3 and secure this metalband and therefore the pad 2 against shifting in lateral direction,"'owing to the fact that they have. bent guide lugs or tongues I. The resilient metal band 4 and the pad 2 can consequently slide resiliently in longitudinal direction on the supporting springs 6 according to the strength of the blow exerted by a type lever in radial direction, the pad being returned into its initial position under the action of the supporting springs.

I claim:

1. A type lever pad attachment, comprising in combination a rigid supporting strap, a pad of elastic material, bent supporting springs fixed on said strap substantially in their middle and bear-' ing against the underside of and loosely supporting said pad to allow said pad to slide in the longitudinal direction on said strap, and guide tongues projecting laterally at one end of said springs to secure said pad against lateral displacement.

2. A type lever pad attachment as specified in claim 1, in which the pad comprises a flexiblemetal band coated with elastic material, the ends of said band being bent over to term a resilient bearing on the strap.

LUDWIG DENZER.

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