213 TRACK-TYPE EXCAVATOR Swing Bearing & Gear Group Caterpillar

Swing Bearing & Gear Group

Fig. WH 130

The swing bearing connection is a single row antifriction bearing. When fitting the connection, make sure that the contact surfaces on the upper end and lower carriage sides is perfectly flat and not contaminated by rust, paint or burrs.

Apply Loctite preparation 275 to the mating surfaces between the rotary connection and the upper carriage as well as between the rotary connection in the lower carriage. To do so, first degrease and clean the mating surfaces and apply the compound immediately before fitting the connection. Between the holes of two parts squeeze a strip of Loctite 275 (approx. 4 to 5 mm wide) out of the tube all the way around the circles of the hose. When the rotary connection is fitted, the Loctite will spread between the mating surfaces and will be activated and harden after about 48 hours. The Loctite 275, with its high shear resistance, relieves strain from the mounting bolts.

The frictional connection is better, as with Loctite 275, only 1/4 of the radial forces are transmitted.

Tighten the mounting bolts to the specified torque. The bushings used on the lower carriage side ensure better expansion behavior of the bolts (extended positive lock length of bolts), and they are hardened on the flat side so that the bolt heads will not sink into them and loosen. The mounting bolts on the upper carriage side are not provided with bushings, since the bolts already possess the necessary length and the internal ring of the rotary connection is of heat-treated material. Secure the bolts with Loctite 242.

The contact areas of the swing bearing connection are inductively hardened. During the hardening process, a "soft spot" usually occurs on the outer race (undercarriage side) and is marked with an "S" or with the trademark of the manufacturer. On the inner race, it coincides with the filler hole, which is closed with a plug. This spot should be positioned in the area subjected to the least load, 90° to the boom.

At the widest point of the toothed rim (greatest eccentricity), three teeth are marked with green paint. It is at this point that the backlash between pinion and gear is measured with a feeler gauge or lead wire. The backlash should be between 0.4 mm and 0.8 mm.

NOTE: Proper lubrication of the swing bearing connector is essential.

1. Contact area.

Grease nipples (fittings) from the main boom bearing are located on the right (as seen from rear of vehicle) on the side plate of the upper frame. A system of ducts delivers the grease to a number of lubrication points in the inner race of the connector. Proper lubrication is ensured if fresh grease oozes (slowly flows) out of the full circumference of the sealing lips. During the lubricating procedure, swing the upper carriage to distribute the fresh grease over the entire contact surface.

The lubricating intervals should be selected in accordance with the operating conditions. In general, this should be done every 100 hours of service. In the case of high humidity or moisture or under very dusty conditions, the connector should be lubricated more frequently.

Good lubrication is especially important before the vehicle is left idle over extended periods and afterwards, as well as after cleaning, e.g. with a steam cleaning apparatus. Always be on the alert for corrosion. Any water that has penetrated into the machine parts must be removed. A good ring of grease reinforces the sealing effect of the sealing lips.

2. Toothed rim

Make sure that the gear teeth are always well lubricated with an adhesive lubricant with EP additives.