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Types of Spanners Explored
Some spanners are made of high carbon steel hardened and tempered or case hardened mild steel. High quality spanners required for special purposes are made of chrome nickel steel, and sometimes chrome vanadium steels.
Spanners are marked with the crest diameter of the bolt whose head they fit. A whitworth spanner fits a B.S.F. bolt one size larger. Classification Spanners are classified by type, material and size of the bolt or nut on which it fits.
The following are different types of spanners which are in common use:
a) Set Spanner: The jaws may be set at an angle of 0 degree, 15 degree or 30 degree to the center line of the handle. This is most common type of spanner, but not altogether satisfactory as it fits the nut or bolt on two faces only and the jaws tend to spring. These spanners are often double ended to fit on consecutive sizes of nuts or bolts. The jaws are set at an angle to the handle for use in constricted areas. A new grip can be got on the nut or bolt by turning the spanner over. The set spanner should always be used in preference to the adjustable type as this gives the correct size across the flats, and the correct type of shank or handle for leverage.
b) Box Spanner, Tube Spanner or “T” handled Box Spanner: These fit the nuts all round and thus avoid damage to them by slipping. They are specifically useful for nuts where the only possible access is from the top.
c) Ring Spanners: These fit nut all round. To facilitate their use, the socket receiving the nut or bolt head is often bi-hexagonal in shape; a ratchet may also be fitted.
d) “C” Spanners: This spanner is used on splined circular nuts.
e) Socket Spanners: This type of spanner can be replaced for box spanners. The sockets are usually bi-hexagonal and are used in conjunction with various extension bars, ratchet handles and universal joints, which facilitate their use and extend their range of application.
Splined Tube Spanner
f) Splined Tube Spanners: These are box type spanners for splined circular nuts.
g) Peg Spanners: This type of spanner has two or more small round pegs which fit into corresponding holes in the special type nut. Drifts or pin punches must not be used instead of the proper peg spanner as they damage and strain the nut.
h) Adjustable Spanners: These are very convenient because of range of size available in one tool. They should not be used if a suitable fixed jaw spanner is available as the jaws have a tendency to spring and damage the nut. It is classified by the overall length.
Crow foot Spanner
i) Crow-foot Spanners: These are used in restricted spaces only.
j) Terry Set or Folding Set: It contains of three B.A. size spanners and they are 2B.A, 4B.A. and 6B.A.