Appeal No. 97-2642 Page 9
Application No. 08/094,461
asphalt paver normally has a hydraulic pump 52 for power
take-off which is usually driven off the tractor engine and is
supplied with oil from a reservoir 53 on the tractor. The
output from the pump 52 is connected by a hose 54 to a
selector unit 55 shown schematically in Figure 8 which
alternately connects with a heat system port 58a or a vibrator
system port 58b. The port 58a is connected to a shuttle valve
62 and a solenoid operated valve 64 arranged in parallel for
controlling supply to a heat system supply line 66. The heat
system supply line 66 connects to a hydraulic motor 76 which
drives a high pressure hydraulic pump 78 taking suction from
an oil reservoir 50. Output from the pump 78 flows through a
primary flow restrictor 82 which functions to heat the oil
responsive to a pressure drop across the restrictor. Most of
the heated oil from the restrictor 82 returns directly to the
reservoir 50 and the balance is divided into two like circuits
at needle valves 84, 85 leading by flexible hoses 86, 87 to
input ends of the heat exchange tubes on the two halves of the
sole plate 16 of the main screed. The hot oil continues from
the main screed to the heat exchange tubes on the screed
extenders 16a by flexible hoses 48 and then returns to the oil
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Last modified: November 3, 2007