Patent Invented by Abraham Chris

GB216799

Patent Number	GB 216799/23
Date Applied For	1923 November 27
Date Issued	1924 June 5
Issued to	Abraham Chris
Assigned to	Not noted
Location	London, England
Current Class/ subclass	N/A

The original is available.

Patent GB 216799, user unknown

In eBay auction 3264402327, there is a item described as:

A large old wooden clamp with 12" jaws opening to 9" wide; it has a brass plate attached with the markings: BRITISH MAKE PATENT NO 216799/23.

This clamp bore no maker mark.

Illustration of Patent

The illustration has 4 figures:

the whole clamp,
a cross section of the jaws,
a view of the inside or operative faces of the jaws, and
details of the handle.

Description of Patent

Quoting the second and later paragraphs of the specification:

This invention relates to an improved hand=screw, which as compared with the ordinary "all-wood" device or tool in general use is more efficient in its action. is capable of exerting greater compression or gripping stress, and generally is less liable to damage or fracture.

... I form them [the screws] of metal - preferably hardened steel - fitted with wood or like handles. ...

The jaw a ... is fitted [with] a metal ferrule or thimble... The cupped end of the ferrule is adapted to constitute a thrust surface for the end of the operating [terminal] screw.

The [other] jaw b is fitted with a pair of internally threaded non-rotatable blocks or nuts with which the screws engage. ... the nuts are arranged on opposite faces of jaw b...results in the thrust of the operating screws (when the tool is in use) tending to thrust the nuts home in their seatings...

... the rivets for each handle are disposed at right angles to one another. ... .

The patent covers three aspects of the clamp:

metal screws, nuts, and ferrule allow greater force to be applied
the strengthened handles are able to handle the greater torque
the faces on the jaws protect the work piece.

last revised and validated