Introduction to Health and Safety at Work

User adjusted guard
These are fi xed or movable guards, which are adjustable 
for a particular operation during which they remain fi xed. 
Figure 11.12
Range of fi xed guards.
Shaft wit projectios
Rack and pinion gears
Axial flow fans
Belt conveyor
Counter-rotating rolls
Pulley belts
Meshing gears
Chain and sprockets

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Work equipment hazards and control
175
They are particularly used with machine tools where 
some access to the dangerous part is required (e.g. drills, 
circular saws, milling machines) and where the clearance 
required will vary (e.g. with the size of the cutter in use on 
a horizontal milling machine or with the size of the timber 
being sawn on a circular saw bench) (Figure 11.13).
Adjustable guards may be the only option with 
cutting tools, which are otherwise very diffi cult to guard, 
but they have the disadvantage of requiring frequent re-
adjustment. By the nature of the machines on which they 
are most frequently used, there will still be some access 
to the dangerous parts, so these machines must only be 
used by suitably trained operators. Jigs, push sticks and 
false tables must be used wherever possible to minimize 
hazards during the feeding of the work-piece. The 
working area should be well lit and kept free of anything 
which might cause the operator to slip or trip.
Self-adjusting guard
A self-adjusting guard is one which adjusts itself to 
accommodate, for example, the passage of material.
A good example is the spring-loaded guard fi tted to 
many portable circular saws.
As with adjustable guards (see above) they only 
provide a partial solution in that they may well still allow 
access to the dangerous part of the machinery. They 
require careful maintenance to ensure they work to the 
best advantage (Figure 11.14).