Reducing wear on the undercarriage [Part 1]

Undercarriage - 22/04/2021

7 operating errors to avoid that speed up wear and tear on the undercarriage of tracked vehicles.

Costs related to the undercarriage represent a substantial fraction of the overall operating expenses for tracked vehicles, representing as much as 50% of total maintenance costs over the working life of a machine.

This is because the undercarriage is subject to heavy loading and external agents during use that wear out the components over time. A low performance undercarriage not only reduces the efficiency of the vehicle, but also risks causing damage to other components, greatly compromising productivity and increasing expense.        
Like all other essential components, an undercarriage requires the right amount of care and good practice to extend its useful life, slowing down wear and substantially reducing maintenance costs.

How can wear be defined and what are the main factors influencing it?

There are numerous definitions of this phenomenon. The American Society for Testing and Materials (ASTM) defines wear as a mechanical loss of material that occurs as a consequence of contact between two surfaces. Generally and by way of example we can talk of:

  • Adhesive wear, originating from the interaction of asperities between two contact surfaces that generate a significant adhesive force which, eventually, leads to localized weldings of the asperities and final breakage and release of small particles.
  • Abrasive wear, which occurs when external particles or a rough hard surface slides over a relatively softer surface.
  • Fatigue wear results from formation of cracks and voids in solid contact surfaces, amplified by continuous variable loading.
  • Fretting is caused by constant cyclical rubbing of minor amplitude between two surfaces.
  • Erosive wear is produced by high speed flow of particles or fluids over surfaces.
  • Corrosion and oxidation wear occurs as a combined effect of chemical and mechanical action.

Undercarriage wear is mainly caused by the first two in the list, and can be worsened by three other main factors, which fortunately we are able to manage and control. These are:

  • Bad habits when using the machine and in particular speed
  • Loading
  • Presence of external abrasive materials

In this article we analyse the first factor, the bad habits of operators when using tracked machines, regarding speed in particular, even though also loading plays an equally significant role in these habits. 

7 common errors to avoid when using tracked machines to reduce undercarriage wear

Over the long term the undercarriage components of vehicles with steel or rubber tracks wear down. However, there are ways to limit this inevitable process, including an appropriate daily management of the machine and undercarriage. Improving operating techniques makes it possible to eliminate the bad habits that cause faults, additional expense, and lower productivity. Below are the 7 most common errors in the use of tracked machinery to correct for more extended undercarriage performance by slowing down the wear process, which nevertheless remains inevitable.

Typical errors that are made with all types of tracked vehicles

1. High speeds in forward and reverse drive 
 

     

It is sometimes advantageous to operate at high speed but this habit accelerates wear on the undercarriage and its individual components, like the links, bushings, rollers, and the drive sprocket and idler wheels. In general, working under full load while maintaining low speed is preferable to working under half load at a higher speed. Even if it might not seem obvious, the first approach gets the job done quicker, saves fuel, and avoids premature undercarriage wear. Driving in reverse can also be hazardous at both high and low speeds. Reverse driving accelerates wear specifically on the bushings and drive sprocket wheels, and so it is advisable only to reverse when really necessary, for short distances, and never accelerating excessively.

2. Unnecessary movements


Some operators tend to use tracked vehicles outside of the work area, for example during the lunch break. This speeds up undercarriage wear at the expense of productivity, while also wasting fuel. For movements unconnected with work operations, it is good practice to use other, more appropriate forms of transport.

3. Sharp steering

   
Counter-rotating a tracked vehicle accelerates wear of the undercarriage components while also generating high non-productive loads that make this phenomenon even worse. It is advisable to avoid this technique unless the working conditions require it: normally sharp steering manoeuvres are almost never really necessary. The best method for turning is to rotate the machine gradually while moving forwards or backwards. Gradual turns are easier to execute, reduce peak loads and undercarriage wear to a minimum, while also limiting potential damage from the failure of the parts involved.

4. Always turning towards the same side


Vehicle wear is inevitable sooner or later, but paying attention to how you turn the machine can even it out. If you always turn in the same direction the undercarriage components on one side will wear out before those on the other side: turning more frequently towards the left, for example, will cause the right hand side to wear out first. Whenever possible the machine should be positioned so that it can turn in different directions from time to time.

Typical errors when using bulldozers

5. Incorrect use of the front blade


To move a bulldozer effectively under full load it is important to pay attention to the position of the front blade while moving. If it remains too steeply angled towards the ground it will continue the digging action even when this is no longer necessary. Wrong blade positioning makes it difficult for the machine to advance, consuming a lot of energy for limited effect while generating excessive loading with the risk of damaging also the blade. At the same time the undercarriage is subject to slippage, which generates wear without any corresponding increase in productivity, ruining the component parts over time. The most effective method is to dig only until the front blade is fully loaded, and then raise it relative to the ground so that the machine can proceed more easily.

6. Wrong ripper angle


Track slippage also occurs during ripping. When the ripper starts penetrating the ground, the back of the machine lifts up creating an imbalance. Maintaining this inclination is a bad habit that applies excessive force to the components at the front of the vehicle, including the forward section of the undercarriage. Once the ground has been penetrated, it is necessary to angle the ripper in the working position so that the weight is more evenly distributed, allowing the machine to advance correctly and extending the life of the undercarriage.

A typical error when using excavators

7. Advancing in the direction of the drive sprocket wheel


The correct way to drive the machine forward is with the undercarriage drive sprocket always at the back. Driving the excavator with the cab rotated to face the drive sprocket end should be avoided. The excavator is able to advance in this incorrect drive position but the undercarriage is effectively running in reverse, unnecessarily overloading its components. Driving in reverse should be limited as much as possible because it accelerates wear on the undercarriage, generating higher maintenance costs.

In the next edition we will discuss the other two factors in detail, loading, and the presence of external abrasive substances, which even more directly impact undercarriage wear and tear.