Broderson RT-400-A, Operation And Maintenance Manual

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SAFETY DEVICES
There are certain safety devices on the RT-400 that are designed to maintain control of a
load even if power or hydraulic line failure occurs. The operator should understand the
function and operation of these devices so that a continual check on their performance can
be made. There are other safety devices on the RT-400 designed to assist in the safe
operation of the crane. These devices work with the control system, hydraulic system or
engine to avert potential hazards. The operator should also understand how these devices
work and how to routinely check if the device is functioning properly.
OUTRIGGER CYLINDER CHECK VALVES:
A double-acting check valve is mounted on each of the outrigger cylinders. This valve holds
the outrigger in the extended position should power or hydraulic line failure occur. This valve
has no adjustment. If an outrigger creeps up while supporting a load, there is an internal
leak in the valve or in the outrigger cylinder piston seal. In either case, maintenance is
required.
BOOM ELEVATION CYLINDER HOLDING VALVE:
A single-acting holding valve is mounted into the cylinder barrel. This valve holds the boom
in the elevated position if power or hydraulic pressure line failure occur. This valve is
adjustable to hold the desired load. If the boom creeps down with loads up through
maximum capacity, valve should be adjusted. If adjustment fails to correct the problem,
there is an internal leak in the holding valve or the hydraulic cylinder. Refer to the main-
tenance instructions.
BOOM TELESCOPE CYLINDER HOLDING VALVE:
A single-acting holding valve is mounted to the telescoping cylinder. This valve holds the
cylinder in the extended position if power or hydraulic pressure line failure occurs. This valve
is adjustable to hold the desired load. If the boom creeps in under load, the valve should be
adjusted. If adjustment fails to correct the problem, there is an internal leak in the holding
valve or the hydraulic cylinder. Refer to the maintenance instructions.
HOIST BRAKE AND HOLDING VALVE:
The hoist has an automatic brake in the gearbox and a holding valve mounted directly on the
hoist motor to hold the load. A clutch in the gearbox allows the winch to turn freely in the
RAISE direction. The brake is pilot - released in the LOWER direction and should allow
smooth stops of a load on the hoist.
ANTI-TWO-BLOCK SYSTEM:
This system prevents damage to the hoist rope and machine components from accidentally
pulling the load hook against the boom tip. A pivot arm-actuated electric switch is connected
through a cable reel mounted on the boom to the control system , to stop the hydraulic circuit.
This system will block the HOIST RAISE, TELESCOPE EXTEND and BOOM LOWER. No
other circuits are affected. These circuits are returned to normal operation by operating the
HOIST LOWER or TELESCOPE RETRACT control. An emergency over-ride is provided so
the boom can be operated in case of system failure. This button is located on the RCL
Display. When the over-ride is selected, a countdown timer is displayed, indicating how long
the over-ride will be active.
W A R N I N G
We recommend the emergency override button be used with discretion. Improper or
careless use of this operation can cause damage to the crane and endanger people
and property. The operator who uses this button in an emergency should use good
judgment.