WEAR AND DEFORMATION OF THE LINK

Wavy wear is typical for machines operating at high speed and with high mileage.

Causes of occurrence

Increased wear at the edges of the links appears because the overlapping area of the links of adjacent constellations, in which one link overlaps the other, is very small and in areas where there is no such overlap, the specific loads increase by 2 times, which leads to such wear. An increase in the link pitch due to internal wear on the pivot increases the wavy effect. The wear in the central part of the link occurs due to the small contact area of the flat surface of the link treadmill and the convex treadmill of the idler, as well as the reduced hardness in this zone due to the outflow of heat into the "strut" of the link during heat treatment.

Factors accelerating wavy wear

Travel speed, weight, machine power, bearing capacity and abrasiveness of the soil, shoe width, track tension. Tracks mounted on bulldozers that have two idler wheels instead of one (some Caterpillar, Liebherr and Shehwa bulldozers) are subject to faster wear.

Effect produced

Premature wear in the area above the pin boss will shorten the life of the track chain. The machine vibrates and shifts from side to side as it travels.

Preventive measures and elimination

• Equip machine with track chain with liquid pivot lubrication (if previously used).
• Maintain the required track tension level for specific conditions .

Intense wear at the transition from the link treadmill to the sidewall. It happens both from the outer and from the inner surface of the link.

Causes of occurrence

• Contact of the links with the flanges of the rollers and the idler wheel.
• Installation of a new track on undercarriage system with already fairly worn out rollers. In this case, the wear pattern of the rollers is transferred to the chain links (arc wear).
• Misalignment of one or more units of the undercarriage system, including the complete tracked vehicle. Roller ribs pull the track chain in line and wear to a minimum along the ribs.
• Installation of tracks or track rollers that are not normally intended for use on this tractor model.

Factors accelerating wavy wear

The same as with wavy wear, as well as the speed of the rollers, the use of wide shoes when working on terrain with high soil density.

Effect produced

Shortened track life due to high pressure generated. New rollers wear out faster if installed and operated with worn track chains.

Preventive measures and elimination

• Replace all components of the undercarriage at the same time.
• Minimize the influence of controlled wear factors on the undercarriage by using the narrowest possible track shoes, alternate direction of travel when working on hills, and check the alignment of the undercarriage.
• Replace tracks with significant «kink».

Wear and chipping on the inner side of the link in one or more places at regular intervals.

Causes of occurrence:

• misalignment between the chain and the drive sprocket;

• track kink when the machine is moving;
• use of inappropriate drive sprocket

Factors accelerating chipping of the inner side of the link

Operation on slopes and using wide shoes.

Produced effect

Reduced likelihood of links and sprockets re-using after repair.

Prevention and elimination

• Correct misalignment and use shoes of the correct width.
• Use track guards.
• Use appropriate drive sprockets

Causes of occurrence:

Rotation of the sleeve in the "pocket" of the link with displacement as a result of the increase in the link pitch. The increase in pitch is due to wear in the bushing-pin pair, which can also be caused by wear on the seal (if present).

Factors accelerating pocket hole elongation

Large width shoes.

Produced effect

Reduced likelihood of links and sprockets re-using when repairing a track chain, even with new seals.

Prevention and elimination

• Overturn of bushings and pins upon reaching their limit wear rates.
• Avoid sudden changes in speeds

Causes of occurrence

• Contact of the boss with the outer diameter of the roller flange due to the fact that the limit wear of the link rail of the rollers and the track links has been exceeded.
• Use of tracks that are not intended for installation on this tractor model (with reduced link height).

Factors accelerating boss wear

Unevenly distributed load on the first track rollers (front or rear) due to specific working conditions (terrain or operation type).

Produced effect

Reducing the tightness in the pin-link fit, which can lead to breakage of the pins, machine downtime and further failure of other components of the undercarriage. It is forbidden to reuse the track links when the bushings and pins are turned over to restore the chains. Strong vibration when operating equipment at high speed.

Prevention and elimination

• Monitor the wear of undercarriage components and repair / replace worn parts in time.
• Compensate for excessive loads on the front or rear part of the machine with counterweights.

A link can be considered susceptible to this problem if more than 30% of the total length of the link is affected. Otherwise, the damage may be considered superficial.

Causes of occurrence

Typically, this is caused by hard impacts when the link treadmill makes contact with the track roller treadmill and ribs. This can happen when installing a new track on worn out rollers. In fact, the high pressure on the small contact surface leads to surface work hardening at the corners of the treadmill of the link. At the same time, this generates the appearance of microcracks under the surface at the places where the maximum load is concentrated. These cracks spread and in a fairly short time lead to spalling of steel fragments.

Factors accelerating pitting

Excessive track tension, wide shoes, impacts, machine speed and weight.

Produced effect

Reduced service life, inability to reuse for repair

Prevention and elimination

• Avoid installing new tracks on worn rollers.
• Eliminate and reduce the effects of controlled wear factors such as correct shoe width and correct track tension.

Structural damage is concentrated at corners and sections of the link with a minimum cross-sectional area.

Causes of occurrence

The main reasons are mainly high torsional or twisting stresses in the links. This is also a common problem associated with the relative wear of track links operating in difficult conditions such as heavy soils, logging operations, etc.

Factors accelerating occurrence of cracks and failures

Same as for treadmill collapse plus treadmill wear. A very important factor can be operation on chemically active soils, in particular on dumps of chemical industries containing even small concentrations of salt, sulfuric and phosphoric acids. As a result of their impact on steel, its sulfide and hydrogen embrittlement occurs, corrosion develops, and in the presence of microcracks and defects in the steel structure from deformation during forging and heat treatment, cracks develop, leading to link breakage. Overly wide shoes are also an important factor.

Produced effect

Machine downtime, non-reusable for repairs.

Prevention and elimination

Reduce or eliminate controlled wear factors such as smaller shoe widths and lower chain tension.

Causes of occurrence

Insufficient tightening of the shoe bolts due to non-observance of the required tightening torque during assembly and maintenance of the track, stretching the bolt body due to their insufficiently high strength class.

Factors accelerating effect

Excessively wide shoes and an excessively high load that can affect the stretching of the bolt body.

Produced effect

Breakage of shoe bolts and shoes and unexpected and costly downtime to replace them.

Prevention and elimination

• Timely (according to the tractor operating manual and the passport for the track) check the tightening torque of the bolts
• Use shoes with a suitable width for the ground and the work to be performed.

Causes of occurrence

Internal wear between the pin and bushing increases the joint clearance S between the pin and bush. The hub axis is offset, which reduces the clearance between the outer diameter of the hub and the link pocket. Subsequently, this leads to the occurrence of friction between these components during mutual rotation.

Factors accelerating wear

Speed, weight, power, applied shoe width and correct track tension.

Produced effect

• Reduced and uneven bushing contacting the seal, resulting in an increased seal failure rate. Increased possibility of abrasive penetration into the hinge.
• Service life is also reduced for remanufactured chains, increased play in the pocket (link / bushing) will facilitate penetration of abrasive particles

Prevention and elimination

• Bushing wear is inevitable in dry chains. The use of oil or grease lubricated tracks significantly reduces internal joint wear, as well as wear on the outer diameter of the bushing at the ends.
• Turning over the bushing and pin before 100% wear rate at the chain pitch.
• Elimination of controllable factors