Types and Features of Wrenches

Double-ended wrench

This is a tool used for tightening and removing bolts and nuts.

Features

• Tightens and loosens by holding two faces (two parallel faces) of a bolt or nut. The head shape may be round or pointed, with the pointed type having a thinner tip than the round type, making it easier to use in tight spaces.
• The open mouth allows fast turning at temporary tightening.

Table of bolt thread diameter and wrench width across flats

Metric thread	Hex bolt/nut mm	Compact hex bolt/nut mm	High-strength hex bolt/nut mm
M1.6	3.2
M2	4
M2.2	4.5
M2.5	5
M3	5.5
M3.5	6
M4	7
M4.5	8
M5	8
M6	10
M7	11
M8	13（14）	12
M10	16（17）	14
M12	18（19）	17	22
M14	21（22）	19（21）
M16	24（26）	22（23）	27
M18	27（29）	24（26）
M20	30（32）	27（29）	32
M22	32（35）	30（32）	36
M24	36（38）	32（35）	41
M27	41	36	46
M30	46	41	50
M33	50	46
M36	55（54）	50
M39	60（58）	55
M42	65（63）
M45	70（67）
M48	75（71）
M52	80（77）
M56	85

(Old JIS indications in parentheses)

Type and class

Type		Class	Symbol indicating class
Type according to head shape	Type according to number of openings
Round shape	Single ended	Normal	N
		Heavy-duty	H
	Double ended	Normal	N
		Heavy-duty	H
Pointed	Single ended	－	S

Single-end open-end wrench

Features

• This type has an opening only on one end.

Combination wrench

Features

• This is a two-in-one functional tool that is easy to use even at home for a wide range of repairs and crafts. The open-end can be used for temporary tightening, and the box wrench can be used for final tightening.

Main points

• Check the width across flats (mm) of the bolt/nut and select a wrench of the corresponding size.
  
• Select the type that best suits the application. (Single ended, double ended, combination, etc.)

Spanner wrench (hook wrench)

With this tool, the claw is inserted into a groove or pin hole and the principle of leverage is used to tighten.

Features

• Used for installation and removal of round nuts and nuts with bearings. Force can easily be applied by turning while contacting the nut at the two points (hook at tip and base).

Adjustable spanner wrench

Features

• Moving the slide enables the tool to accommodate a wider range of diameters.

Hook pin wrench

Features

• Force can easily be applied by turning while contacting the nut at the two points (pin at tip and base).
• Used when the part to receive a round nut (shape where force is applied) is a round hole.

Main points

• Check the shape of the claw (hook or pinhole type).
  * The shape of the claw (hook or pin hole) must match the shape of the groove or hole where force is applied on the round nut or the wrench will not be usable.
• Check if the diameter of the object to be tightened is within the wrench’s range of use.

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