AP-1050B and BG-245C Asphalt Pavers Caterpillar

Hydraulic Screed Counterbalance System

Usage:

The screed counterbalance system applies hydraulic pressure to the rod end of the screed lift cylinders. The screed counterbalance system does the following tasks:

While the machine is paving, the screed counterbalance system reduces the mark that is created when the operator stops the machine.
The screed counterbalance system transfers the weight of the screed to the paver in order to reduce the settling of the screed.
In some cases, the screed counterbalance system reduces the wear of the screed wear plates.

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Illustration 1	g00746720
(1) Screed counterbalance control (2) Tester button (3) Pressure gauge

To read the pressure of the screed counterbalance system, push tester button (2) inward and hold the tester button. Read pressure gauge (3) while you hold the knob.

An adjustable relief valve controls the hydraulic pressure to the screed counterbalance system. The pressure at the rod end of the screed lift cylinders should be 515 kPa (75 psi), when adjusting screw (1) is turned completely in the counterclockwise direction. The pressure will be indicated on pressure gauge (3) .

Turn adjusting screw (1) clockwise in order to increase the pressure of the screed counterbalance system. Increase the pressure in 172 kPa (25 psi) increments in order to correct problems with the mat that are caused by the setting of the screed. Check the mat in order to determine that the desired results are being achieved after you adjust the pressure of the screed counterbalance system.

Note: If the pressure of the screed counterbalance system is increased above 1035 kPa (150 psi), the mat density may be affected. The mat density will have an open texture and the mat may require additional compaction from the compactor.

Note: If the pressure of the screed counterbalance system is increased above 1035 kPa (150 psi), the automatic grade and slope controls may be affected. The higher pressure can cause the screed to not float and the higher pressure will affect the ability of the grade control to maintain the proper elevation. An indication of a high pressure setting is a grade that does not match the joint properly. A wavy mat can also result from the pressure that has been set improperly.