TRB Transportation Research E-Circular E-C013
off for that function and the booms cannot be moved into a position that would allow the equipment to become unstable. In most cases, operation of the unit can continue if the function that was being operated when the unit shut down is reversed.
Remote Control System
The remote control system is located at the platform and is one of two varieties:
Electrical control handles (some times called joysticks) may be used to control the functions of the unit from the platform. The sticks transmit an electrical signal to electrical solenoids mounted on the main control valve. These control sticks are usually proportional and allow the operator to vary the amount of deflection applied to the control handle in order to control boom movement speed.
Another version of this system is the use of toggle switches. Toggle switches are not proportional; however, some valve manufacturers have designed valves to work with toggle switches. These valves meter the hydraulic flow and are sometimes referred to as soft-touch valves.
On some aerial equipment, a hydraulic valve with handles may be mounted on the platform to provide operational control of the boom(s). This type of system is commonly referred to as a full hydraulic system.
Safety Shutdown System
Safety shutdown systems are a very important feature of modern aerial equipment. Shutdown switches are usually located inside of the truck cab, main control valve, and platform. Location of these switches depends on what type of work the equipment is performing. For instance, in a mobile operation such as inspection of bridges, the booms may be deployed and the driver of the truck may not be able to see the entire length of the booms. The platform operator may shut down the truck to prevent the booms from hitting a portion of the bridge structure.
TYPES OF INSPECTIONS
There are four generally accepted types of inspections that are performed on aerial equipment:
Frequent Inspections, and