HOUSING 8N0441 - Caterpillar

TRACK-TYPE TRACTORS
The testing of track-type tractors can be done by one man. The oil-cooled brakes provide the loading medium to be used while testing a tractor. With oil-cooled brakes, there is only a slim chance of overheating occurring in the brake drums, but caution is advised in this area because extended periods of extreme brake application may overheat and damage the brake drums.1. Provide adequate clearance around the tractor in the test area. Generally this test can be conducted in a distance of about 150 feet (50 meters).2. Operate the tractor in third range with the throttle in the high idle position. On tractors with torque converters, it is very important that the tractor be hot.3. Operate the brakes to bring the engine down from high idle to the desired full load rpm. This should occur before the torque converter stall speed.WHEEL LOADERS
The techniques used for wheel loaders is somewhat similar to that of track-type tractors. It is an inmotion type test using the vehicle brakes as the prime method of applying the load. If convenient, the bucket can be loaded with dirt to provide additional weight to the vehicle; this will reduce the load requirement of the brakes. (Torque converter stall speed will normally occur at a higher rpm than full load.) Since the brakes on wheel loaders are not oil-cooled, caution should be used to prevent overheating of the brake drums. It is also possible to operate the hydraulic controls against the relief valve to provide additional loading. If a hydraulic "tee" test is also being performed, connect the "tee" test equipment and use the manual load valve to increase the system pressure for exact control of the load; use torque converter stall for primary loading.MOTOR GRADERS
The loading technique for motor graders is similar to that used for wheel loaders except that a load cannot be added to the machine. It is not recommended to attempt to load the vehicle with the blade. Instead, the operator can use the transmission to accelerate against. It is desirable to have a grade of 3% or more when testing motor graders.OFF-HIGHWAY TRUCKS
The testing of off-highway trucks requires an engine analyst with machine handling experience; but preferably, the regular operator should drive the truck while the analyst uses the other seat to run the test. If it is possible to load the bed of the truck, the test procedure will be simplifed. If not possible, then a 3 to 5% grade will be needed for the test. On machines with an eight-speed transmission, select the fourth range and accelerate to the desired engine rpm.TRACTOR-SCRAPERS
Tractor-scrapers equipped with a hydraulic retarder are comparatively easy to load. If the facilities are available, fill the scraper bowl with dirt. The additional weight will reduce the need of using the retarder and the possibility of overheating the torque converter. Whenever the retarder is used to apply additional load, observe the converter temperature gauge very closely. DO NOT LET THE TORQUE CONVERTER OVERHEAT. The operator can