300 Hydraulic System
12. Lower the relief pressure on the regeneration valve by unscrewing the adjustment screw until the
oil flows through the regeneration valve drain (adjust to a drizzle of oil of about 1/8’’ to 3/16’’).
13. Lock the relief adjustment screw on the regeneration valve with a locknut.
14. Stop the engine.
15. Reinstall the drain line.
16. Adjust the main relief valve pressure to the required value (2000 PSI [±50 PSI] for trucks with a
4x2 chassis or 3000 PSI [±50 PSI] for trucks with a tag axle or a 6x4 chassis).
17. Reconnect the fully extended packer proximity switch that has been disconnected in Step 1.
18. Test the newly adjusted pressure by running a compaction cycle.
19. Test the electrical response of the system: Increase the engine RPM when the packer moves
forward.
The packer should change speed (slowing down) when the engine reaches 1000 RPM.
Checking Tailgate Hydraulic System
The main valve is designed in such a way that the tailgate cylinders are pressurized in closing position
when the other functions are used. As for the velocity fuse, it drains the piston end of low flow
cylinders (no tailgate movement). When the tailgate opens, the velocity fuse locks itself to prevent
the tailgate from lowering by itself. The following procedure is used to ensure good working
condition of the tailgate hydraulic system.
To check the tailgate hydraulic system:
1. Fully open and close the tailgate three times to ensure there is no more air in the tailgate
hydraulic system.
2. Open the tailgate to 90 degrees (tailgate in horizontal position) and keep it in this position for
10 minutes to check that it does not lower slowly.
3. Ensure the tailgate section spool enters when the tailgate closes and comes out when it opens.
4. Make sure a velocity fuse is on the air actuator side of the valve tailgate section.
5. Ensure the presence of a holding valve on the tailgate-closing hydraulic line and that it is
connected as follows: Port “D2” to the air actuator side of the valve; Port “D1” to the opposite
side of the valve; Port “U1” to the rod side of each tailgate cylinder; Port “U2” to the piston side
of each tailgate cylinder.
6. Connect 2 pressure gauges to the valve tailgate section: Gauge #1 (0@4000 PSI) to the spool
side of the valve and Gauge #2 (0@4000 PSI) to the air actuator side of the valve.
Close the tailgate completely. By pressurizing the subsequent sections (e.g. packer, body), make sure
the pressure on Gauge #1 reaches the main relief pressure, that is 2000 or 3000 PSI, depending on the
adjustment made to the main relief. The pressure on Gauge #2 must remain at 0 PSI.
Hydraulic Cooler Maintenance
NOTE: For units equipped with a hydraulic cooler fan (see Figure 5-45).
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