2016年5月17日星期二

Bronze(polyamide) bush for Peugeot & Citroen Rear Axle Beam

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Bronze(polyamide) bush for Peugeot & Citroen Rear Axle Beam is used for prolonging its life. This problem can be solved in different ways. It is known, that even the rear beam axle of high quality isn’t able to work for a long time, if its surface is outworn by the destroyed needle bearing.

These are mostly the needle bearings of the rear beam, which cause difficulties with the whole rear beam. There are some cases known, when the bearings of the famous brands were to be changed after 50000 kilometrage.
needle bearing



Sometimes one may try to replace the needle bearing with something else. But the problem is, that the needle bearing of Peugeot, Citroen, Samand has the specific construction and little size. The specificity of the construction is in the absence of the inner race, that’s why the needle rollers move on the surface of the rear beam axle. The rollers are very thin, which is the reason why the height of the bearing is small.  There are the bearings in twos at both sides. One bearing is placed on the outer edge of the axle and is totally covered from one butt end, the other one is placed on the axle, nearer to the centre of the car and has a stuffing box. The covered butt end of the outer and the stuffing box of the inner bearing prevent from water getting in the middle of the unit.
bearings in twos at both sides
Enlarge image

This is hard, to find an appropriate substitute for the needle bearing of the rear beam of Peugeot, Citroen, Samand without making fundamental changes in the whole unit and still saving qualitative characteristics of the suspension.

Nevertheless the bearing bush can still serve as an alternative to the needle bearing. A plain bearing, manufactured of the special materials, is quite often used under the certain circumstances.

Two main parameters should be defined for producing the bush: material for it and its proportion. This seems to be not that difficult on the face of it, but the definite problems can be turned out after starting working on it.

The polyamide bush of the rear beam is mostly used because of its advantageous friction coefficient, in spite of its minor hardness (both — when compared with the bronze bush).

Using bushes as the plain bearings in place of the needle bearing in the rear beam lever has its advantages and disadvantages:

Advantages:

    the rear beam bush from polyamide or bronze are not sensitive to moisture
    when destroyed, are not that destructive for the surface of the rear beam lever slot
    can be used as a temporary measure, when it is impossible to replace rear beam pins or axles. At greater length – in the article Temporary measure.

Disadvantages:

    lower friction coefficient
    low hardness
    absence of packings, stuffing boxes, which prevent from moisture getting to the rear beam lever
    increase of the suspension hardness
    absence of guaranteed measurement
    risk of fake. That can occur accidently or on purpose of cost reduction, when the wrong material for the bush is chosen.

Learn about some difficulties in the article Measurement of the bearing bushes of the rear beam of Peugeot, Citroen, Samand. Rear beam bushes, serving as the plain bearings, can be used as a temporary substitute to the needle bearing under the certain circumstances. If you hope to prolong the life of the rear beam axles and pins with the help of the bushes, you should remember, that as opposed to the needle bearings bushes hardly prevent from water getting into the unit of the rear beam lever. This is moisture, which breaks down the pins having high hardness, but no corrosion protection. Appeared rust, even when not progressed, comes to the bearing bush plane endwise and rubs it hole as abrasive hasting its wear.

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