/ Gain in Running Gear Service Life
"ChTZ-Uraltrac" Ltd developed production of the bogie wheels with the friction bearings for the running gear of the industrial tractors manufactured by the Chelyabinsk Tractor Plant.
The friction bearings allow taking the high specific loads. Therefore the reliability of such rollers mounted on the pipe layers and on the tractors operated together with the heavy attached implements is much higher than the reliability of the rollers equipped with the frictionless bearings.
The engineering solution (patent for the model No 32079 from 5.05.2003) used for the design of the rollers Кат-21-169СБ-Б/170СП-Б developed by the classical scheme provides the minimum axial clearance non adjustable with the gaskets. This clearance does not exceed 0.4 mm: it is lower by 1.6 than on the production rollers with the frictionless bearings. It makes possible considerable increasing of the reliability and the service life of the seals and the end bearings.
The bogie wheels are equipped with the seals "Duo Cone" 1 (see Fig.) which provide the safe performance even under conditions of the heavy wet grounds and of the alternating temperatures.
The bronze 010С10 GOST 613-79В of the thickness from 0.7 to 0.9 mm is used as the bearing antifriction material. The roller axle 6 is made of the steel 38ХС; the hardness of the axle working part exceeds 46 units HRC.
The bogie wheels Кат-21-169СБ-БЛ70СП-Б were successfully tested under various conditions including the rock and sand environment when the quartz content exceeds 95%, to the extent of the warranty service life.
As a result of the work carried out by our engineering services the following actions increasing not only the quality of the track but also its service life were undertaken:
- 1. The special-purpose machining stations were designed, manufactured and implemented to improve the track link rail hardening. The required depth of the burnt layer is provided.
- 2. Two broaching machines were mounted to machine the shoe nut fit surface. As a result, the defect of nut loosening during the operation is remedied. (Earlier the machining was carried out on the straightening machine.)
- 3. Six diamond-boring machines are mounted. The control of the complete machining of the holes for pressing of the pin and the bushing with the stable providing with the step dimension (203 mm) as well as of the hole machining cleanliness is increased. As a result, the track joint mobility has been improved as well as the secured tension at the pin and bushing pressing-in has been provided. Two pressing machines by "Marum" company were introduced to assemble the tracks.
- 4. The shoe nut hardening was applied, which increased the reliability of the shoe fastening.
- 5. The shoe steel grade 40Г1Р was changed to the high-alloy steel 32ХФР.
- 6. The drum-milling machine is introduced for simultaneous machining of the mounting and running surfaces of a link.
- 7. The milling tools of the Swedish company "Sandwik-Karomant" (Сандвик-Каромант) were applied, which improved the machining surfaces cleanliness and the dimensional stability.
- 8. The steel grade 20Г used for the track link bushings was changed to the high-alloy steel 20ХГНР, which provided with the hardness 59-65 НRС after treatment on the existing thermal equipment.
- 9. The double-action press machines were put into operation for the hydraulic forging of the bushing by the elastic deformation method.
- 10. The connector minimal axial play is reduced 6.5 times, which comes to 0.15 mm.
- 11. The track links 50-22-7-01 and 50-22-8-01 with boring of the holes for the pin pressing-in are applied to increase the reliability of a pin-link connection.
The above-mentioned measures allow increasing the track service life up to 20%, particularly when operating on the watered grounds (hydraulic alluvion) with the high content of the abrasives.
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