Mechanical tools

MECHANICAL TOOLS

WRENCHES HAND TOOLS

Objectives

• identify the different wrenches used
• state the features of each type of wrenches

Types of wrenches 

1. Still-son pipe wrench
2. Footprint pipe wrenches
3. Tension wrenches
4. Hexagon socket wrenches

Still-son pipe wrenches : These are used for gripping and turning pipes of a wide range of diameters. 

         

    

         A jaw is fixed to the handle with outward facing teeth. attached to the handle by a pivot pin is a spring-loaded casing that caries a knurled adjusting nut. this engages with a thread on the adjustable arm of a jaw with inward facing teeth.

once a jaw is adjusted, the spring loading keeps them in contact with the work, and the toggle action causes the hardened serrations to bite into the work.

• The jaws will mark the work. 
• Fill off any burrs.
• Never use them on polished or plated surfaces.
• Never grip hardened materials with this type of wrench as this will damage the serrations.

Footprint pipe wrenches : These are used for gripping and turning pipes and round stock, particularly in confined spaces.

             Adjust the size by fitting the removable pin in the hole that allows the pipe to be gripped, with the handles a comfortable distance apart. Thrust the jaws fully on to the pipe. Squeeze the handles firmly. pull on the folded steel handled to turn the pipe. stop squeezing and slide the jaws back round the pipe, squeezes and pull again.

Fill of any burrs raised by the jaws on the pipe.

Tension wrenches : A tension wrench acts as a torque limiting device for turning (rotating) nuts to a predetermined degree of tightness. This avoids breaking the the fasteners. it also essential to avoid wrapping or springing components held by multiple fasteners that could be unevenly tightened, cylinder heads of engines, for example.

                                             

            Some tensions wrenches have direct reading indicators that you must watch as you pull the handle to the desired extent. with others, you preset to the desired graduation and pull until you detect a signal which may be an audible clicks, the release of a trigger pin or an automatic release within the wrenches mechanism.

Hexagonal socket wrenches : These are hexagonal section bars of tool steel bent to 'L' shape. they are sometimes called Allen keys.

            These are used to rotate set screws having internal hexagon sockets. they are available in sets ranging in sizes from 1.5 mm to 20 mm across the flats. 

Make sure that socket and wrenches are clean before use. Use the correct size. Insert to the full depth. discard if the ends become worn out or rounded as they are liable to slip under load.