15.3.9 Portable Conveyors, Extending Belt Conveyors, And Car Unloaders
The raising and lowering mechanism for the boom of a portable conveyor shall hold the boom
at any rated angle of inclination. A powered extendible conveyor shall be operated with constant
pressure button control and be equipped with a device located on the outermost boom end that
shall stop extension of the conveyor when contact is made with the device (as may be required to
protect personnel): Portable conveyors shall be stable and will not topple when in use or when
being moved. Guarding may be necessary with the boom in its lowest position.
15.3.10 Pusher Bar Conveyors
If a hazard exists where the bar passes through the bed at the discharge end, suitable guards or
warnings shall be provided. Loads on the incline shall have pushers of adequate height above the
bed or have top restraining members. All chains should be guarded by suitable means, including
warning signs, to prevent accidental contact with the moving chain. In a pusher bar conveyor
having a roller bed, where the relationship between the height of the bar and the spacing of the
rollers creates a hazard, adequate guarding must be provided. When a shear point exists between
the return pusher bar and a frame member, guarding shall be provided. When the conveyor is
automatically loaded, an automatic spacer shall be provided. When a pusher bar conveyor
discharges to another conveyor, means shall be provided to stop the pusher bar conveyor in the
event the receiving conveyor cannot accept another load.
15.3.11 Roller And Wheel Conveyors
When unit or package speeds could create a safety hazard limiting the length of the pitched run
or by using speed retarders, brakes or other means that effectively provide the control needed
shall be employed. Personnel shall not be allowed to walk or step on free turning rollers or
wheels. Suitable means, such as tread plates, can be used between the rollers as a walking
surface for designated operators in the performance of their duties. Rollers and wheels must be
free running to prevent unintentional diverting of units being conveyed.
15.3.12 Screw Conveyors
Screw conveyors shall not be operated unless the conveyor housing completely encloses the
conveyor moving elements, and power transmission guards are in place, except if the conveyor
must have an open housing as a condition of its use and application. The entire conveyor is then
required to be guarded by a railing or fence, unless guarded by location.