TB24 Plus&26J Plus Maintenance Manual 6-1 © Jun 2022
6 REPAIR PROCEDURES
Repair procedures shall be
completed by a person trained and
qualified on the repair of this
machine.
Immediately tag and remove from
service a damaged or malfunctioning
machine.
Repair any machine damage or
malfunction before operating the
machine.
Before machine startup：
• Read, understand and obey the
safety rules and operating
instructions contained in
operation manual.
• Read all procedures and rules.
• Unless otherwise specified,
perform each repair procedure
with the machine in the following
configuration:
– Machine parked on a firm, level
surface.
– Platform in the stowed
position.
– Key switch in the OFF position
with the key removed.
– All wheels choked.
BOOM AND PLATFORM
COMPONENTS
Boom and Platform Systems
Broken Cable Indicator System
The boom of this machine is a 3–section proportionally
driven telescopic boom. The first telescopic boom is
cylinder-driven, the second telescopic boom is driven
by a seperate wire rope system. Rope system contains
redundant ropes that are capable of allowing the
operator to continue use of the machine with a single
rope failure. The retract cable is installed outside the
boom so that the failures with retract cable are self-
revealing to the operator. Failures with the extend cable
require the addition of the Broken Cable Indicator
System in order to be self-revealing to the operator.
This system uses a proximity sensor to detect
excessive movement of the sensed rope as would be
expected with a rope failure. A broken cable detection
results in illuminating the indicator on the ground
control display panel and triggering the alarm, and such
functions as boom extending and raising are restricted
while boom retracting and lowering is permitted. It is the
responsibility of the operator to take the appropriate
action.
Platform Control Enable System
The platform controls make use of a time dependent
enable circuit to limit the time availability of “live” or
enabled controls. When the footswitch is depressed,
the controls are enabled and the operator has 7
seconds to operate any function. The controls will
remain enabled as long as the operator continues to
use any function and will remain enabled 7 seconds
after the last function has been used. While the controls
are “live”, the enabled light will be illuminated in the
platform display panel. When the time limit has been
reached, the enabled light will turn off and the controls
will be “dead” or disabled. To continue use of the
machine the controls must be re-enabled to start the
timer system over again. This is done by releasing all
functions, then releasing and re-depressing the
footswitch.
Boom Position Sensing System
The boom position sensing system uses the boom
angle sensor and boom length sensor mounted in the
pivot end of base boom to indicate the boom position.
The boom operating position is recognized when the
angle sensor reads more than 15° with respect to
gravity or the length sensor reads more than 1.2m
extension, otherwise it indicates that the boom is in the
non-operating position. The jib boom position is
excluded from consideration.
This system is used to control the following systems：
• Drive Speed Cutback System
• Axle Extension System
Drive Speed Cutback System
When boom is positioned in operating position, the
drive motors are automatically restricted to the
operating speed mode.
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