Section 6
Recirculation System
20412963
8-2012/Rev 07
6-2
Figure 6-2: Recirculation System Components (Oil-to-Water)
The recirculation pump pulls oil from the reservoir and sends it to the heat exchanger. The oil-to-
water heat exchanger controls heat build-up in the hydraulic oil. The plate style design allows
cooling water and oil to flow side by side through alternating plates.
The cooled oil then passes through the filter element and returns to the reservoir. The cooling
water either is discharged to the 1/2-inch NPT drain on the rear bulkhead or is routed to a
customer supplied water chiller.
The hydraulic oil filter assembly consists of the filter head, a filter element, pressure gauge or
indicator, bypass relief valve and the oil fill port. All 30, 50 and 60 horsepower machines are
equipped with a numeric pressure gauge that indicates inlet pressure. The filter element should
be changed when the gauge reads 40 psi (2.8 bar) at normal operating temperature. The 100
horsepower machines utilize a differential pressure indicator. The filter element on these
machines should be changed when the indicator enters the red zone at normal operating
temperature.
If the element is not replaced, and fills with debris, the bypass relief in the filter head will open to
prevent over pressurization. The relief valve opens at 50 psi (3.4 bar) on 30, 50 and 60
horsepower models, 25 psi (1.7 bar) on 100 horsepower models. When the valve opens, the oil
bypasses the filter and unfiltered oil is allowed to return to the reservoir.
The temperature/low level switch monitors the oil temperature and level in the reservoir. An
automatic shutdown will occur if the operating oil temperature exceeds 144 F (62 C). An
automatic shutdown will also occur if the oil level on a 30, 50 or 60 horsepower machine falls
below 28 gal (106 L). Low oil level shutdown occurs at 37 gal (140 L) on a 100 horsepower
machine.
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