PowerBoss Nautilus Hi-Dump PB45HDSL, Service Booklet

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The green “ALL ON-OFF” switch also provides power for the proportional valve driver which controls the
Proportional reduction valve SV4 (Main brush force).
The operator selects the desired brush scrubbing force by turning the brush force rotary switch, located
on the instrument panel, to one of three switch positions, low, medium, and high. The rotary switch
provides three separate signals to the proportional valve driver input terminals IN B and IO 2.
IN B low and IO 2 low = Low brush force
IN B high and IO 2 low = medium brush force
IN B low and IO 2 high = high brush force
With a brush force selected, the proportional valve driver sends a signal to the proportional reduction
valve SV4 which controls the hydraulic pressure that is applied to the rod-end of the scrub head lift
cylinder. This pressure acts against the controlled pressure which is constantly applied to the piston-end
of the cylinder causing the scrub head to lower and providing the correct brush force against the floor.
A note on the operation of the scrub head lift cylinder:
The hydraulic pressure supplied by the proportional reduction valve alone would provide more scrub
brush force against the floor than is desired. For this reason a constant balancing hydraulic pressure of
450 psi is applied to the opposite side of the cylinder piston. In addition, when the pressure is removed
from the proportional reduction valve, the 450 psi balancing pressure is utilized to raise the scrub head
to its storage position.
Additional scrubbing control switch and timer:
When the scrub brushes are down and turning but the machine is not in motion, a neutral switch,
located on the hydraulic propulsion pump mount, opens triggering a true-off-delay 5-second timer
(motion timer). If the machine remains motionless for 1.5 seconds the timer will interrupt the electrical
power to solenoid SV2 (all on-off)and SV3 (main brushes on) which will turn off the scrub brushes (the
flow of cleaning solution will also turn off). As soon as the machine starts to move the neutral switch
closes, the timer returns power to solenoid SV2 and SV3, and the brushes turn on.
CMK 9-17-2015