Meyer E-58H, Service Manual

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SOLENOID SWITCH
The E-58H, E-78 & E-88 motor requires more current
or amperage to operate than the vehicle wiring, vehicle
ignition switch or toggle switches have the capacity to
handle. The solenoid switch is essentially a heavy duty
switch with the capacity to handle the heavy current
required by the motor. It is closed electrically by the
solenoid to convey the heavy current directly from the
vehicle battery via heavy gauge electrical cable. The
solenoid, which functions essentially the same as the
previously described solenoid valves, receives its low
amperage current at the proper times via the wiring
harness. This solenoid must be grounded to operate
properly.
FILTERS
Cleanliness is perhaps the single most important
ingredient in assuring a hydraulic system’s reliability.
Should the hydraulic fluid become contaminated,
malfunction and permanent damage to the hydraulic
system may occur. For this reason, all the E-58H,
E-78 & E-88 units are equipped with a filter system
consisting of:
• A fine screen strainer on the reservoir pump inlet.
•A high pressure filter on the pressure side of the
pump.
•A return filter on the power angling block leading
back to the reservoir..
With this system, the hydraulic fluid is filtered as it
leaves the reservoir on its way to the pump and on
the Power Angling units filtered again as it leaves the
pump. Because clean hydraulic fluid is most important
to insure Solenoid Valve reliability, the hydraulic fluid
leaving all cylinders is filtered before passing returning
to the reservoir. The filter screen, high pressure and
return filter are easily removed for periodic cleaning
or replacement.
IMPORTANT:
Should the hydraulic fluid become contaminated, it
will be necessary to replace all the hydraulic oil in the
system. The complete system (hydraulic unit, power
angling cylinders, mount cylinder and hoses) should
be flushed. Flush the system with Meyer Hydra-Flush™
Fluid M-2.
ELECTRO LIFT® UNIT COMPONENTS CONT.
CHECK VALVES
Check valves are very simple devices that have two
basic functions: They prevent fluid from passing
through them in one direction, but they allow fluid to
pass through them in the opposite direction.
In the E-58H, E-78 & E-88 a pump check valve is used
to prevent hydraulic fluid from leaking back through
the pump to the reservoir.
The E-58H, E-78 & E-88 unit uses one check valve
located between the “B” Solenoid Valve and the lift
cylinder. It prevents the hydraulic fluid in the lift cylinder
from leaking back through the “B” Solenoid Valve
which could cause the plow to drift down.
DOUBLE ACTING PILOT CHECK VALVE
The pilot check valve is more sophisticated in that
it incorporates a piston in addition to the ball, seat
and spring. It is located between the “C” and “D”
Solenoid Valves on the E-88 and next to the “C”
valve on the E-58H & E-78. It has two functions: The
first is to prevent the hydraulic fluid in either power
angling cylinder from leaking back to the reservoir.
The second is to allow the hydraulic fluid from the
retracting power angling cylinder during the angling
cycle to return to the reservoir. This is accomplished
by the pressurized hydraulic fluid moving the piston
which forces the check ball off its seat. The E-88 also
uses an additional pilot check valve located next to
the “E” valve. This allows the “E” valve to control the
mount/dismount function.
CROSSOVER RELIEF VALVE
When plowing snow, a snow plow can be exposed
to damaging forces caused by impact with hidden
obstructions, ends of curbs, etc. With power angling,
these damaging forces can damage not only the snow
plow but also the vehicle. The crossover relief valve
has the function of protecting the snow plow system
against these damaging forces under normal snow
plowing conditions. The crossover relief valve, cannot
protect the system from damaging forces that are too
great due to abusive snow plowing conditions.
Basically, the crossover relief valve functions
exactly like the previously described pump relief
valve. It’s designed to open at a specific pressure.
In this instance, the pressure is not produced by
the pump but rather by the damaging force. As an
example, assume that the right corner of the plow
runs into the end of a curb. The impact will attempt to
collapse the right power angling cylinder. As a result,
very high hydraulic pressure is produced within the
cylinder. When the produced pressure is high enough,
it opens the crossover relief valve, allowing the highly
pressurized hydraulic fluid to flow directly to the left
power angling cylinder.
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When the crossover relief valve functions in this
manner, the excessive pressure is released, the
excessive energy produced by the impact is absorbed,
and the result is only a change in angled position of
the plow.
The crossover relief valve is factory set to the specified
pressure of 3800 P.S.I. ± 400 this setting is non-
adjustable.