[quote=&quot;admin&quot;:1keutbcr]The 1850 is an open center hydraulic system, so you can't just return to the reservoir. The pressurized oil needs to complete the circuit in order to power everything else in the tractor hydraulic system. Depending on what you have for a speed control valve on your rake, you could return the oil from the hydraulic motor to the reservoir, while the rest of the oil completes the circuit through the remote. This would make the circuit for the motor a three hose setup, pressure out from the tractor, pressure return to the tractor, and a third hose to return oil from the hydraulic motor to the reservoir. 

Opening the interlocks and the bypass allows the oil to return to sump without 'deadheading' and blowing the relief valve. In an open center system, the oil is always moving, and so it always needs a place to go. Using a single acting cylinder on a circuit that is set up for double acting causes the pressure to back up, feed through other circuits and open the relief valve. Some of this is inherent to open center systems, and some of it is because of the unique Oliver design.[/quote:1keutbcr] 
Thanks for the information the manuals were not real clear on the interlock and bypass. Darryl