General requirements for car repair

The main part of mechanical malfunctions of knots and units in operation is due to the process of friction, deformation elements, the aging of the parts, etc. These and other processes entail wear and damaged parts. How to wear can be divided into three periods: the running-in, normal wear and alert. In the process of running an intensive wear of friction parts, resulting in unevenness of the mating surfaces are reduced, increasing the contact area, the specific load is reduced, the wear rate is slowed down and returns to normal wear and tear. The period of normal wear and tear is characterized by relatively low growth rate of the gap in conjugation, but by a certain gap wear rate increases sharply, indicating the start of an emergency wear. Operating the machine with emergency wear leads to breakdowns, which make it difficult and expensive recovery. In operation, it is important to expose the node before the emergency repair wear and tear.

Before deciding to repair it is necessary to diagnose the status of interfaces in the units. Generally, diagnosis is carried out by circumstantial evidence, such as increased noise, vibration, oil consumption, a breakthrough crankcase gases and others. For better diagnostics unit must be disassembled, parts wash, inspect and carry out measurements. As a result of the inspection and measurement of the decision to continue operation without repair or making repairs. It should be guided by the following considerations: if the actual dimensions of parts are within the fields of tolerance allowed by these Guidelines, the continued operation of the unit without repair possible; if the size exceeded the permissible tolerances, the necessary repairs. Expanding fields of tolerances in this manual must be understood as the use of a residual resource of host interfaces without recovery. In case of repair of the unit in the reduction of interfaces field extension over the nominal tolerances are not allowed.

Repair technologies can be divided into four main stages:

1. Dismantling - washing.

2. Control - Sorting.

3. Actually repair: restoration of micro and macro geometry of surfaces and physico-mechanical properties of parts.

4. Build a preliminary control of parts arriving at the assembly.

Disassembly and washing operation is carried out in several stages: the outer washing machine, podrazborka, nodal sink, on the dismantling of parts, washing and cleaning of parts. All items to the control-sorting should be thoroughly cleaned of dirt and varnish, degrease, rinse and dry. The oil channels and holes in parts to clean, rinse under pressure and blow compressed air.

Details of aluminum and zinc alloys are not allowed to wash in alkaline solution used for cleaning steel and cast iron parts, as aluminum and zinc are soluble in alkalis.

In the process control of parts breakup, cracks, dents and other damage to the shell detect by visual inspection. At critical parts checked for cracks using a flaw. Dimensions of parts must be monitored in the most exposed areas. Gear teeth wear unevenly, and when the control should measure at least three teeth arranged at an angle of 120 ?�. Given the need to ensure continued gears during the turnaround spalling on the teeth and the working surface of the teeth vykroshivanie fatigue nature are not allowed.

Assembly units - such as a rod with a cover of a rod, a cylinder block with main bearing caps, gear transmission and the main transfer can not razukomplektovyvat. The rest of the assembly units can be razukomplektovyvat; if the decision to continue operating mating elements without decoration, they razukomplektovyvat inappropriate.

In all cases, parts repair welding and surfacing weld must not have slag inclusions, undercooked areas, undercuts and other defects.

After welding the joint clean. Spatter removed, so they do not interfere with the installation of mating parts.

Holes worn or damaged threads is reduced, cutting the threads larger oversize, brewing holes followed by threading the nominal size, staging and vvertyshey spiral threaded inserts. The use of threaded inserts is preferable for reasons of quality of recovery and reduction of labor costs.

Details supplied to the assembly, must be clean and dry. Threaded connections must be free of damage. Disposable self-locking threaded fasteners must be replaced with new ones. If you are unable to use new self-locking parts in the formulation of their old need to further loosen the stopper on.

When assembling installing new gaskets and seals. Rubbing the surface of the parts about the assembly to lubricate clean oil. In setting up the cuffs of their working surfaces should be lubricated to avoid damage during installation. When installing cuffs with metal casing jack under the collar should be coated with a thin layer of sealant.

The assembly of components and assemblies must be performed in accordance with the manual.

Use the measuring tools to check the dimensions prior to assembly of parts that make up the landing.

When assembling the parts in conjunction with a movable landing should be provided free of relative movement without jamming. Sleeves, rings ball and roller bearings installed using mandrels. When pressing the bearing force should not be transmitted via balls or rollers. Tools for pressing must rest on the press-fit ring. Direction pressing force should coincide with the axis of the bearing to prevent misalignment.

If the terms of the build installation of critical parts made with a hammer, it is necessary to use a mandrel and hammer-ferrous metals, plastics, rubber, as well as accessories for fitting parts.

The keys must be firmly planted in the shaft keyways with a hammer, or mandrels of non-ferrous metal. Backlash dowels in slots shafts is allowed.

Studs should be wrapped tightly into the threaded holes without play. Items must fit over the stud bolts. Podgibaniem studs when installing them is not permitted parts, fastening assembly or parts of several nuts or bolts must be done uniformly on the perimeter - first preliminary and then final.

In all the cases provided for guidance necessary to apply the keys that allow to limit torque.

Tightening torques, unless specifically stipulated in the technical conditions are determined depending on the diameter of the thread in accordance with the Table. 13.

Bolt must protrude from the nut (unless otherwise specified) in two-three strings of thread.

Pins must not protrude from the slots nuts. The ends of the pins should be diluted and bent - a bolt and a nut on the other.

Tubes fuel and brake actuator assembly is necessary to blow compressed air.