: Refer to Figure 3. 15. When illuminated this indicates the function
active. On initial selection, the MODE SELECT light caption flashes and LOW
illuminates. Movement of the joystick forward will select the high bridge drive logic and
the HIGH caption illuminates. Movement of the joystick rearward selects the low bridge
drive logic and the LOW caption illuminates.
The bridge drive logic setting is determined by the height of the far bank and reference
should be made to Chapter 1 Section II Table 1.11 for the correct setting.
This mode selection alters the tension in the upper and lower winches. In HIGH mode the
upper winch becomes the primary driving winch as the bridge tends to run back towards
the launch vehicle. In LOW and LEVEL mode the lower winch becomes the primary
driving winch as the bridge tends to run towards the far bank.
Once the bank condition is selected i.e. HIGH, LOW or LEVEL a further movement of the
joystick to the right selects that condition for all further operations. The MODE SELECT
caption goes off, the bank condition chosen stays illuminated and the TILT ROLLER
caption located next to the left hand joystick illuminates as does the roller brake function.
This indicates that the left hand joystick is now functional and is set for extending or
retracting the tilt roller cylinder. Operation of the tilt roller joystick will now move the tilt
roller, forward to raise, rearward to lower.
Intermittent flashing of the TILT ROLLER and ROLLER BRAKE lights indicates that the
roller brakes have not been applied and that the tilt rollers are currently non functional.
The upper and lower winches are fitted with winch tensioners, in addition the upper winch
cable is monitored by a winch cable tension indicator. The winch cable tension indicator
operates a micro switch. The limit switch is monitored via the firmware and is only
functional in a HIGH BANK build, as it is only in HIGH BANK that the top winch is driven
proportionally via the joystick. In all other instances, the upper winch is either applying
back tension, which is trying to pull in cable or the cable, is being pulled off the upper
If the cable does go slack and the limit switch trips then the winch can no longer be driven
so that more cable is paid off. The operator is made aware of this by the FAULT light on
the chest pack flashing along with the TOP WINCH light, which is located to the far right
of the chest pack menu. This method of identifying the fault gives a clear indication that
the fault is top winch related.
Should the top winch cable become slack and set off the micro switch, the joystick should
be moved rearwards to pay in cable and hence re-tension the cable. It should be
confirmed that the correct selection has been made for the conditions for the bridge build.
i.e. is HIGH bank being used in a LEVEL bank situation.
As stated, the cable tension sensor is only used in the HIGH bank mode. It is disabled for
TOP WINCH (Para. 188.8.131.52)
as this mode
is used for replacing cables
on to the drum
during which slack is likely to occur.