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|  MIL-T-62021E(AT)
3.5.3.4 Engine components. The engine fuel supply shall be provided by the truck chassis
fuel tank. A fuel pump and filter shall be provided. The muffler shall be positioned so that the
fumes do not interfere with the operator.
3.5.4 Water pump. The water pump shall be of the positive displacement reciprocating
type. The pump shall be capable of delivering a minimum of 227 L/m (60 gallons per minute
(gpm)) against not less than a 540 790 kPa (1650 psi) head at 500 revolutions per minute (rpm)
maximum. The drive shall be multiple "V" belt or direct from the power takeoff, and shall be of
adequate size to transmit the power from the auxiliary engine to the pump without slippage.
When a multiple "V" belt is furnished, a screw jack type tensioning device shall be provided on
the engine so that proper tension can be maintained in the belts. Positive means to prevent total
shutoff of the outlet of the pump shall be provided. A multi-purpose valve shall be incorporated.
This valve, in the proper position, shall direct the flow of water to the cleaning nozzle under
increased pressure or provide water to the wash down hose or direct the water to the recirculatory
system as required.
3.5.4.1 Piping. All high pressure piping, both pipe and fittings, shall be of steel and shall
be adequate for continuous operation at pressures up to the maximum output pressure of the water
pump with adequate provision for over pressure. Piping shall have a safety factor of not less than
4 to 1. All suction and low pressure return lines may be of standard weight pipe and malleable
fittings. Cast iron fittings shall not be used. The piping system shall be designed so as to
facilitate complete draining of the entire system.
*
3.5.5 Hydraulic drive system. The hydraulic drive system that powers the hose reel shall
consist of a five gallon tank, a return line filter with replaceable element, a direction and speed
control valve with built-in overload relief, a dual counterbalance valve to provide hydraulic shock
relief, a speed control valve, high pressure hoses with integral swivel type fittings, a pump driven
by the power takeoff or the auxiliary engine and a reversible hydraulic motor. The hydraulic
motor shall be of the gearotor type capable of delivering at least 960 Newton meters (N m)
(8500 inch pounds) of torque at the hose reel shaft.
*
3.5.6 Controls and control panel. All gages, switches, levers and control valves necessary
for the control of the operation, shall be grouped together at the operator's station so that the
operator shall have complete control of the cleaning operation at all times. A fixed control panel
shall be provided and shall contain as a minimum a choke (gasoline engine only), a vernier-type
throttle, an ammeter, an engine water temperature gage, an engine oil pressure gage, a low water
warning light, a key type combination ignition starter switch, a reel speed control, a reel hydraulic
system pressure gage, a water system pressure gage and a quick disconnect type of connection for
the wash down hose. Convenient access to the rear side of the controls and gages mounted on the
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