SENSOR GP-TEMPERATURE 2380112 - Caterpillar

AGRICULTURAL TRACTORS
CHALLENGER 35 (8DR, 8RD, ADK),
CHALLENGER 45 (1DR, ABF, 3BK),
CHALLENGER 55 (7DM, 6NN, AEN),
CHALLENGER 65E (6GS),
CHALLENGER 75E (6HS),
CHALLENGER 85E (6JS),
CHALLENGER 95E (6KS) AGRICULTURAL TRACTORSProblem:
Additional heat is added to the hydraulic system when a down pressure circuit is plumbed for air seeder applications. This is due to the down pressure circuit causing the implement system to run at high pressure stand-by while the fan circuit requires less system pressure. The difference between the fan circuit pressure and high pressure stand-by, times the fan flow that can be anywhere between 45 to 68 L/min (12 to 18 gpm) is all added heat to the hydraulic system.Solution:
The following instructions outline the principle of operation, installation procedure, and necessary parts to install a pressure limiting network for a constant down pressure circuit. This rework procedure will allow the hydraulic system to function optimally without adding any additional heat.Principles of OperationThis circuit is designed to limit the load sense (LS) signal sent to the pump from the "lower" port of the down pressure circuit. During "raising", the LS signal is not limited. This is necessary to get adequate raise times of the openers. The manual valve is in the circuit so that the "pressure limiting" circuit can be turned off when using other implements on circuit #1. By pulling the knob out and rotating so the roll pin sits on the upper level of the valve body will turn the "pressure limiting" circuit on. By rotating, and pushing in to the lower position on the manual valve, the "pressure limiting" circuit is disabled.The LS signal from the "lower" side of the down pressure circuit is sent to the specialized primary resolver with an orifice. The orifice limits the oil that can be bled out of the sequence valve that lowers the power loss. The LS signal is sent down the valve stack to section #2 where it is pulled out of the valve stack by the specialized secondary resolver plug that is installed. The LS signal is then branched at the tee in the resolver plug. One line from the tee goes to a resolver valve that resolves section #1 with the other sections. The other line goes to the sequence valve that bleeds off oil to maintain the desired work port pressure. The LS signal acts against the spring in the sequence valve. By turning the adjustment screw, the spring force is changed, thus varying the work port pressure. By measuring the LS pressure sent to the pump, set the pressure to approximately 8620 kPa (1,250 psi). This will ensure adequate pressure for the down pressure circuit. Oil bled off by the sequence valve is then routed through the manual on/off valve and back to the return screen on the machine.The line that is teed into the "raise" work port of the down pressure circuit is used as a signal to be able to attain full system pressure while rising. The signal is directed to the spring end of the sequence valve.