(3) Inspection For Leakage. - During each day's run the operator should take the time to make a visual check of
the exposed parts of the system for evidence of fluid leakage. Early detection of a leak will prevent extensive loss of
fluid and unnecessary down-time.
Figure 5 - Line Filter & Filter Condition Gauge
(4) Filter Element Change - (Figure 5.) The 10 micron filter element on the side of the fluid reservoir should be
changed after the first month of operation or when gauge reading indicates a filtering restriction as explained in
Paragraph (5). Subsequent element changes should be made each 250 engine hours to assure good fluid passage.
(5) Filter Gauge Readings - A new filter element produces a reading of less than 5 when the engine is at full
throttle, the hydraulic fluid is hot (150° F or above) and no hydraulic component is being operated. As the element
becomes restricted by contaminants from hours of normal paver operation the gauge reading will rise. When the
reading stays above 15 at all times during operation, with the same conditions as listed above, the filter element
is badly restricted and should be changed! Do not take a gauge reading when any of the hydraulic cylinders are
(6) Hydraulic Fluid Change - The fluid reservoir should be drained completely, flushed clean and re-filled with
fresh fluid at least once a year. When the reservoir is empty the fill screen and the large 100 mesh suction strainer which
are both attached to the cover should also be cleaned. Back-flush the strainer by forcing cleaning solvent thru the
suction pipe in the cover. (See Figure 6.) Use clean hydraulic fluid to rinse all components after they are cleaned with
Figure 6 - Reservoir - Exploded View
(7) Hydraulic Pump - The hydraulic pump is capable of delivering 10 to 12 G.P.M. of hydraulic fluid to the valve
bank at the required pressure when the paver engine speed is 2000 r.p.m. At slower speeds the pump output flow rate
and pressure capability is reduced.
The pump requires no adjustment, however, V-belt driven units will lose efficiency if belt tension is not correct and
slippage around the pulleys occurs. Belt tension should be checked at regular intervals.
The pump must be able to build 1,200 PSI pressure on a test gauge installed in the pressure line to the valve bank
when engine is at full throttle and screed switch is held in "UP" position. (Pressure relief valve must be working properly).
Replace or repair a pump which cannot maintain this pressure.