Usage:
Challenger 65C (2ZJ) Challenger 70C (2YL) Challenger 75C (4KK) Challenger 85C (9TK) Tractors
Pneumatic front idlers have been replaced with solid front idlers on C-Series machines. The pneumatic idler supplied a significant amount of recoil. In order to replace this lost recoil, the tension cylinders have been redesigned to combine a nitrogen boost for a longer travel spring. The nitrogen gas compresses when recoil is needed. A thorough understanding of nitrogen and its response to temperature change is necessary to properly service the tension cylinders and to achieve maximum life of the undercarriage components.
Nitrogen charge pressure varies with temperature. As the temperature decreases, the nitrogen pressure decreases. In instances when the ambient temperature is below the temperature referred to in the chart, the nitrogen pressure may decrease such that it is just below the set point of the low pressure alarm system.
The low nitrogen pressure alarm system detects an inadequate nitrogen charge in either tension cylinder. A buffer compares the actual pressure to a set point. If actual pressure falls below this set point, the alarm indicator light on the dash turns on and the alarm horn is activated. Two versions of the buffer exist and their differences are detailed in the following chart.
For example: If the machine is equipped with the 105-2228 Buffer and tension cylinders are properly charged, the dual alarm systems are activated at temperatures at or below -18°C (0°F). If equipped with the 107-3578 Buffer, the dual alarm systems are activated at temperatures at or below -32°C (-25°F).
NOTE: The 107-3578 Buffer may directly replace the 105-2228 Buffer in areas where ambient temperature falls below -18°C (0°F).
In a low temperature situation in which the alarm system is activated, determine that the actual nitrogen pressure is below the set point and confirm that there are no other system problems. Add enough nitrogen to the cylinder to achieve a pressure above the set point. By adding 10 psi of nitrogen to cylinder, the temperature at which the cylinder reaches the set point pressure is lowered approximately 20°F.
For example: At -18°C (0°F) the pressure in the cylinder is 1220 kPa (177 psi), the alarm system set point for 105-2228 Buffer. By adding 10 psi, the machine has the capability to work in temperatures of -18°C (0°F) to -28°C (-20°F).
NOTE: When the ambient temperature INCREASES, the pressure in the cylinder INCREASES.
The extra nitrogen pressure added to the cylinder during cold weather operation is extra system pressure in warmer months that should be discharged, otherwise front idler bearing life might be compromised. See chart below for proper system pressure at a given ambient temperature. Adding more than 20 psi above the pressure shown in chart for a given temperature is not recommended.
For procedures to test and charge the tension cylinder, refer to service manual module SENR5262, for the topic, Test and Charge The Tension Cylinder.
Contact the Agricultural Machinery Unit for operating instructions for temperatures below -40°C (-40°F).
When servicing the nitrogen system, be sure that the nitrogen temperature has stabilized so that it is the same as the ambient temperature, (for example, if the nitrogen was stored in a cold place and was brought into a warm shop, let the nitrogen temperature stabilize so that it is the same air temperature as the shop). The nitrogen gas does increase in pressure as it warms up to the shop temperature. Cold nitrogen gas added to the tensioning cylinder may result in excess pressure when the gas warms.