Usage:
Challenger 35 (8DN),
Challenger 45 (1DR),
Challenger 55 (7DM),
Challenger 65 (7YC),
Challenger 65B (7YC),
Challenger 65C (2ZJ),
Challenger 65D (2ZJ),
Challenger 70C (2YL),
Challenger 75 (4CJ),
Challenger 75C (4KK),
Challenger 85C (9TK) Agricultural Tractors
Reference: Service Magazine: June 27, 1994, page 2, "Return Line Bypass For Challenger Agricultural Tractors". Service Magazine: June 27, 1994, page 5, "Power Beyond For Challenger Agricultural Tractors". Service Magazine: November 6, 1989, page 2, "Procedure For Attaching A Laser Controlled Scraper To The Hydraulic System".
When running continuous flow hydraulic equipment such as orbital motors, it is important to minimize the heat load generated in the system. Heat usually comes from two sources: inefficiencies in the motor due to work by the implement, or pressure drop caused by restrictions in the system. Restrictions such as in-line orifices and/or bypass valves (used in some open center systems), small diameter hydraulic hoses, very long hydraulic hoses, and small quick disconnects all contribute to heat build up in the hydraulic system.
One of the best ways to improve hydraulic oil flow and reduce restriction in the system is to bypass the implement valve and go directly to the implement. This is commonly referred to as a "power beyond" configuration. Many types of equipment have remotely mounted control valves that control the flow of oil directly to the equipment, eliminating the need for regulation at the machine.
Challenger Agricultural Tractors provide power beyond hookup on "C" Series machines through the use of power beyond tees installed in the implement valve end cover. Challenger 65, 65B and 75 machines did not come factory equipped with a power beyond end cover, but can be retrofitted if desired (see Service Magazine: November 6, 1989, page 2, "Procedure For Attaching A Laser Controlled Scraper To The Hydraulic System"). Even though connection points were identified, the use of O-ring fittings made the implement connection unique and non-standard, as well as inconvenient to connect and disconnect.
The parts listed in the following table can be used to adapt power beyond tees and return oil ports to use low-pressure quick disconnects.
Adapters are available, item 5 and 6 in Illustration 1 and Parts List shown above, to fit the more common hose fittings on implements. Be aware that most implements are equipped with hoses that are too small in diameter for the flow requirements. It is common to see 1/2in. or smaller hoses used in lift or motor circuits that should have 3/4in. or larger hoses. Hoses that are too small cause excessive restriction in the system, and result in low flow and low pressure reaching the motor or cylinder. To minimize restriction in the system, do not adapt inadequate hoses to use the above fittings. Install hoses that better meet the needs of the implement and match the size of the quick disconnect fittings.
The quick disconnects available can be used in power beyond and return line bypass applications on all Challenger Agricultural Tractors. These quick couplers have a lower pressure drop than the couplers on the machine, and provide improved ease of use. The following paragraphs describe the usage on the different models.
Illustration 1. (A) Challenger 35, Challenger 45, and Challenger 55 Agricultural Tractors low pressure return port. (B) Challenger "C" Series Agricultural Tractors "power beyond" tee. (C) Challenger 65B, Challenger 75 Agricultural Tractors (with oil coolers).
Challenger 35 and Challenger 45 Agricultural Tractors
The quick disconnect can be used for low pressure return oil from the motor. A port for this purpose is located to the left side of the PTO clutch housing on the rear of the differential case. The motor supply (pressure side) should be attached to the lower (-) coupler (right side of the machine) in the #1 hydraulic valve. Using this method, the oil flow avoids the restriction caused by the load check valve in the quick coupler manifold.
NOTE: When the #1 (priority) hydraulic valve is being used, it is very important to adjust the flow control to the minimum required for the circuit. Reducing the flow to the minimum required will free up more flow for the remaining circuits, as circuit #1 has absolute priority over the remaining circuits.
In addition, the operating pressure of the orbital motor should be checked by running the implement in the work cycle. High working pressures (> 13780 kPa (2000 psi)) indicate excessive restriction due to small lines, an in-line restrictive orifice, or an in-line variable bypass valve on the implement. To correct this situation, the in-line orifice should be removed or the variable bypass shut off. The motor speed should be regulated through adjustment of the machine flow controls instead of the implement mounted motor speed controls. Heat build-up will be reduced by providing metered flow from the machine implement valve and by eliminating the restriction at the implement. If the cause for high pressure in the system can not be found, or is inherent in the load because of improperly sized motor or cylinders, then the supply line should be moved to the #2 hydraulic valve. Flow priority valve #1 will restrict flow to the other valves and three-point hitch when valve #1 is operated at high pressure.
Challenger 65C and 65D, Challenger 70C, Challenger 75C, and Challenger 85C Agricultural Tractors
The quick disconnects shown in the parts list above can be used on both the supply and return line tees for power beyond applications (See Service Magazine articles referenced above for description of the tees). If the supply line is connected to a tee, a signal line from the implement must also tee into the signal line on the machine. The use of the supply line power beyond connection requires that the implement have SIGNAL LINE CAPABILITY. In order to function correctly, the implement should have a resolver to correctly resolve signals from the power beyond application and the machine's implement valve. The resolver should also have an internal drain to bleed off signal pressure when no demand is seen in the circuit. If an internal drain is not available and a ball resolver is used, the pump will not destroke and will remain at high pressure standby until leakage bleeds off signal pressure.