BENDIX SD-08-2415A manual Operation & Leakage Tests Also see Video BW2327

For Bendix® AD-RP™PuraGuard® oil coalescing air dryers only: Preventive Maintenance is as easy as 1-2-3

Adhering to a preventive maintenance schedule is crucial to keeping a vehicle’s air system clean and to help ensure superior performance of all components that utilize system air — such as brakes, emissions equipment and automated manual transmissions. Depending on vocation, Bendix recommends a 1, 2 or 3-year air dryer cartridge replacement on vehicles equipped with a Bendix® compressor.

For severe service application — such as residential refuse trucks or school buses — the air dryer cartridge should be replaced every year or every 100,000 miles. For pick-up and delivery operations, or for double- and triple-trailer line haul trucks, replacement is recommended every two years or 200,000 miles. Line-haul operations using a single trailer should swap the fi lter out every three (3) years or 300,000 miles. The recommended intervals for trucks equipped with non-Bendix compressors are 6 months (50,000 miles), one year (100,000 miles), and two years (200,000 miles), respectively.

More frequent intervals may be required depending on a vehicle’s age, its compressor condition, use of a non-Bendix compressor, the operating environment, the vehicle’s vocation, and its usage. In conjunction with these guidelines, fl eets can determine the functionality of their

filters by checking for moisture in the air brake system monthly. If moisture is present, the air dryer cartridge may require replacement. Refer to the Bendix Service Data Sheet of the specifi c air dryer for additional information.

This air dryer is intended to remove moisture and other contaminants normally found in the air brake system. Do not inject alcohol, anti-freeze, or other de-icing substances into or upstream of the air dryer. Alcohol is removed by the dryer, but reduces the effectiveness of the device to dry air. Use of other substances can damage the air dryer and may void the warranty.

OPERATION & LEAKAGE TESTS (ALSO SEE VIDEO BW2327*)

1.Check for excessive leakage around the purge valve. With the compressor in the loaded mode (compressing air), apply a soap solution to the purge valve exhaust port and observe that leakage does not exceed a one (1) inch bubble in fi ve (5) seconds. If the leakage exceeds the maximum specifi ed, service the purge valve assembly.

2.Check for leakage around the desiccant cartridge. With the compressor in loaded mode (compressing air), apply a soap solution around the desiccant cartridge

seal and observe that no leakage occurs. If leakage is noted, tighten the cartridge using a strap wrench and re-test for leakage.

3.While observing the dash gauge(s), build up system pressure at approximately 1,800 engine/compressor rpm to governor cut-out. Note the pressure on the dash gauge(s) at the moment governor cut-out occurs and that the Bendix® AD-RP™air dryer purges with an audible escape of air. Observe the dash gauge(s) pressure for two minutes after the purge cycle begins. The front axle service (secondary) and the rear axle (primary) reservoir pressures should not drop more than 2 psi below the governor cut-out pressure noted. Perform this test three times to positively confi rm the values. If the pressure drop in the reservoirs exceeds 2 psi, check the air brake system for excessive leakage and repair.

Build up system pressure to governor cut-out, wait a minimum of 30 seconds for the purge cycle to complete, then apply and release the service brakes to reduce system air pressure to governor cut-in. Note that the system once again builds to full pressure and is followed by an Bendix AD-RP air dryer purge.

4.Check the operation of the heater and thermostat assembly in the body during cold weather operation (if possible) as follows:

A. Electric Power to the Heater and Thermostat

With the ignition or engine kill switch in the ON position, check for voltage to the heater and thermostat assembly using a voltmeter or test light. Unplug the electrical connector at the air dryer and place the test leads on each of the pins of the male connector. If there is no voltage, look for a blown fuse, broken wires, or corrosion in the vehicle wiring harness. Check to see if a good ground path exists.

B. Thermostat and Heater Operation

Turn off the ignition switch and cool the body assembly to below 40° F.

Note: If this test is performed in warm weather (above 30° F) it may be necessary to remove the heater and thermostat assembly and cool it in a freezer.

Using an ohmmeter, check the resistance between the electrical pins in the connector. The resistance should be

1.5to 1.7 ohms for the 12 volt heater assembly and 6.0 to

6.9ohms for the 24 volt heater assembly. If the resistance is higher than the maximum stated, replace the heater and thermostat assembly.

Warm the heater and thermostat assembly to over 90°F and once again check the resistance. The resistance should exceed 1000 ohms. If the resistance values obtained are within the stated limits, the thermostat and heater assembly is operating properly. If the resistance values obtained are outside the stated limits, replace the heater and thermostat assembly.

* Available through the Bendix Marketing Center on www.bendix.com

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