Usage:
12G, 14G, 16G, 120G, 130G, 140G Motor Graders
- SUPPLEMENT: 03/03/80
SERVICE MAGAZINE, JANUARY 28, 1980, PAGE 3. Put a mark through the article "New Cross-Over Steering Relief Valve Used". Both the above article and the article "Steering System Improvements Prevent Possible Damage To Steering Cylinder Sockets" on pages 4, 5 and 6 of the August 27, 1979 Service Magazine have information about the 3G7448 and 3G8436 Relief Valve Groups. Because the article in the August 27, 1979 Service Magazine has information needed to adapt the steering system improvements to earlier motor graders, use it instead of the article in the January 28, 1980 Service Magazine.
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Description of Change: A new cross-over steering relief valve is used on the above model motor graders. The new valves give better protection against pressure spikes (very high pressure for short periods of time). Also, the relief pressure setting has been lowered from 2500 psi (17000 kPa) to 2390 psi (16480 kPa) because of the ability of the valve to go back into its seat. These pressure spikes some times damaged the plastic inserts on the steering cylinder mounts. The new relief valves, two per machine, are inside the valve groups. These groups are on each side of the bolster.
Formerly, the steering relief valves were together on the right side of the bolster.
Adaptable To: The new 3G7448 Relief Valve Group is a replacement for the former 3G8436 Relief Valve Group for the above model motor graders. Installation of the new relief valve on earlier "G" Series Motor Graders is not practical because of the many parts necessary for the change.
Schematic of steering circuit. 1. Steering wheel; 2. Cross-over relief valve; 3. Cross-over relief valve; 4. Plug; 5. Oil return lines to tank; 6. Steering metering pump; 7. Plug; 8. Shims; 9. Shims; 10. Oil supply lines from pump; 11. Left steering cylinder; 12. Right steering cylinder; 13. Oil return lines to tank; 14. Shims; 15. Steering pressure reducing valve; 16. Plug.