ENGINE AR-COMPLETE 2175670 - Caterpillar

The 311 & 312 RUBBER BELT TRACK HYDRAULIC EXCAVATORS is a high performance excavator designed and manufactured by Caterpillar.This manual, intended as a supplement to the OPERATION GUIDE for the standard version, contains only information exclusive to RUBBER BELT TRACK version.To assure long, productive, profitable machine life, thoroughly read and understand this manual as well as the OPERATION GUIDE for the standard version, before operating or performing lubrication, maintenance or repair on this machine.Rubber Belt Tracks Adjustment
Check/Adjust
It is recommended to check and adjust the new rubber belt tracks at Every 50 Service Hours or Weekly within the initial 200 service hours, and then when required.
Grease is under high pressure.Grease coming out of the relief valve under pressure can penetrate the body causing injury or death.Do not watch the relief valve to see if grease is escaping. Watch the track or track adjustment cylinder to see if the track is being loosened.Loosen the relief valve one turn only.If track does not loosen, close the relief vaive and contact your Caterpillar dealer.Do not allow anyone to be under the machine that is raised with only a hydraulic jack. If necessary to work under a raised front attachment, be sure to use appropriate blocks to support the machine.
Keeping the track properly adjusted will increase the service life of the track and drive components.The track, tension has to be set as required by the current operating conditions. Use as slack a track as possible if the soil is heavy.
Measuring Rubber Belt Track Tension
1. Place the upper structure at a 90 degrees angle to the tracks and lower the bucket onto the ground. Gradually apply boom down pressure until the track on that side is lifted off the ground. Use appropriate blocks under the lower frame to support the machine, as shown above.2. Operate the raised track until the CAT marking embossed on the track is positioned directly above the track carrier roller as shown.3. Measure the maximum amount of track sag, A, from the bottom surface of the undercarriage frame to the top point of the core iron. Properly adjusted rubber belt tracks will have approximately 115 to 120 mm (4 1/2 to 4 3/4 in) slack.Adjusting Rubber Belt Track Tension
Track Tightening
1. Add grease through fill valve fitting (1) until the correct track tension is reached.2. Operate the machine back and forth to equalize the pressure.3. Check the amount of track sag again and adjust as necessary.Track Loosening
1. Loosen relief valve (2) carefully (one turn maximum) until the track begins to loosen.2. Tighten relief valve (2) to 34 N m (25 lab ft) when the desired track tension is reached.3. Operate the machine back and forth to equalize the pressure.4. Check the amount of track sag again and adjust as necessary.If the correct adjustment cannot be obtained, consult your Caterpillar dealer.Rubber Belt Track Operation
The rubber part of the track assembly can easily be damaged during operation. The operator can continue to use the rubber belt track as long as rubber belt