1728 Orbit Way - Minden, Nevada 89423 P: 775-782-1700 F: 775-782-1701 info@maxtonvalve.com www.maxtonvalve.com
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CAR AT REST–SOLENOID COILS DE–ENERGIZED
The car at rest is held by a hydraulic fluid system locked in place by a check valve, solenoid pilot valves and a
manual-lowering valve.
UP DIRECTION
When an up call is registered and the pump starts, the up solenoid (U) and the up stop solenoid (US) are
simultaneously energized; closing ball checks US and UT, the pump output flows through the up valve and
back to the reservoir.
Hydraulic fluid from the pump travels through the up control fluid strainer to the by-pass sizing adjustment,
then the control side of the up piston. The control side of the up piston is larger in area than the area of the up
piston exposed to the pump pressure; therefore, the up piston begins to move rapidly towards the up valve,
restricting the opening in the up valve, raising the pump pressure. When the pump pressure reaches a point
slightly below the pressure on the jack side of the check valve, the fluid coming through the by-pass sizing
adjustment is shut off. Then, the fluid from the up acceleration adjustment (UA), which also comes from the
control fluid strainer, causes a continuing movement of the up valve. Fluid begins flowing from the up control
fluid strainer through a ball check to the down piston holding it firmly in position. This allows the guide end of
the down check assembly to act independently as a check valve. As the pump pressure increases above that
on the jack side of the check valve, the check valve is opened, allowing fluid to flow to the jack cylinder,
causing the jack to move in the up direction. The elevator then accelerates to full speed as the up piston
closes the up valve.
Upon reaching a predetermined distance below the floor to which the car is traveling (2 inches for each 10
fpm of car speed NOT to exceed 6 inches for every 25 fpm of car speed), the up solenoid (U) is
de-energized, allowing fluid from the control side of the up piston to flow through the up transition adjustment
(UT), then to the up leveling speed regulator (LS) orifice which is held open by a mechanical linkage attached
to the check valve. The control fluid then returns to the reservoir and the up piston moves toward the open
position. As the up piston moves, opening the up valve, hydraulic fluid begins flowing to the reservoir,
reducing the pump pressure. As the pump pressure is reduced, the check valve begins closing, also, partially
closing the (LS) orifice in the up leveling speed regulator.
When the flow through the (LS) orifice equals in quantity, the flow through the maximum up acceleration
adjustment (UA) and the up leveling adjustment (UL), the car will be in leveling speed. Upon reaching a point
slightly before the floor (usually 3/8 of an inch to 1/4 of an inch), the up stop solenoid (US) is de-energized.
This allows fluid to flow through the up stop adjustment (US), causing the up piston to fully open, permitting
the total pump output to flow to the reservoir, causing the car to stop. After the car comes to a complete stop,
the pump motor is then electrically timed out and stops. If, during up movement, the car has been overloaded
or hits an obstruction, the fluid on the control side of the up piston is evacuated to the reservoir through the
relief valve, causing the up piston to cycle open and by-pass the entire pump output.
OPERATING SEQUENCE UC4, UC4M, UC4MR B44
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