Reach stacker machine
To ensure the smooth flow of goods through ports, specific equipment is required. This includes reach stackers, responsible for moving containers in confined spaces. These vehicles transport heavy loads over long distances and long periods. Their quick maneuvers and tight turns put considerable stress on tyres, resulting in severe and irregular tread wear. This can lead to reduced operational efficiency, additional maintenance, and increased costs. Over the past few years, Michelin's port tyre experts have worked continuously to innovate and develop a product dedicated to answering the needs of reach stackers. To gain insight into the issue of uneven wear, the mechanics related to it, and the use of reach stackers, we discussed with Boris Piol, Michelin Industrial Tyres Product Manager.
Reach stackers operate on the counterweight principle to prevent tipping when carrying heavy containers on the extended boom. They facilitate the loading and unloading of goods from trucks, trains and barges, whether the containers are laden or empty.
Reach stackers have a drive front axle and a steer rear axle.
Michelin's experts analyzed reach stacker behaviour and concluded that the vehicle's movements and weight balance put significant stress on the tyres. By analyzing each cause and its consequences, they decided to optimize a specific tyre design.
When the reach stacker is loaded, its center of gravity shifts to the front axle, causing it to act as a pivot between the container and the rear counterweight. This weight redistribution to the front increases the stress on tyres during maneuvers, such as sharp turns in tight spaces. The figure below illustrates the difference in trajectory between the front tyres (green) and the rear tyres (red).
MICHELIN X STACKER 3 tyre on a machine
The front tyre axle comes in a double fixed assembly, commonly known as a "twin". Because of this robust construction, both shoulders of the tyres on the same twin, unfortunately, cannot travel an equivalent distance while the machine is turning; this distance difference is directly dependent on the turning radius of the vehicle. During a typical 90° turn of a reach stacker, the distance between the two shoulders of the same front tyre can differ by more than twice, resulting in significant slippage of the outer shoulders toward the twin. This causes conical wear, also known as taper wear. This irregular wear, from one shoulder of the tyre to the other, unfortunately, leads to preemptive removal of the assemblies
What may seem like a normal or innocuous problem can be solved. If left unaddressed, conical wear on outer tyres can negatively impact productivity and result in unscheduled maintenance. Typically, customers will either rotate their tyres or remove them as a preventative measure. However, both options can lead to the reach stacker being stopped for almost the day, which can have a significant impact on operations and result in financial losses. And if we talk sustainability for a second, changing tyres more often and not getting the full life out of them results in more material waste. Conical wear manifests itself as follows.
Conical Wear (accelerated phenomenon)
Intensive use of reach stackers can cause premature tyre wear, which can have a significant impact on operational productivity. Not to mention, excessive tyre wear can lead to significant safety issues, putting both operations and personnel at risk.
In 2022, Michelin's radial port tyre development team introduced the MICHELIN X STACKER 3 HD tyre to the market. The mission since 2011 was clear: reach stackers need to operate at full capacity while maximizing tyre life and optimizing the efficiency and profitability of port operations.
According to Mr. Piol, this innovation resulted from several design loops to the tyre construction that significantly improved performance:
We can't do anything to improve the behaviour of the machines, but we can make sure you get the most out of the tires. We have adapted the tread pattern design of our MICHELIN X STACKER 3 HD tyre by strategically adding rubber where it was most needed.
The innovations of the MICHELIN X STACKER 3 HD are reflected in tread design, casing ply, crown belt structure and bead construction. The engineering team aimed to ensure the tyre could complete its lifetime without any endurance problems. Mr. Piol notes that MICHELIN X STACKER 3 HD benefits from the latest rubber materials to greatly reduce the environmental footprint due to the optimized rolling resistance. The tyre was also developed with a focus on aesthetics:
It has a truly unique look. The tyre has an atypical tread pattern, square and massive, which is much more in tune with its use.
MICHELIN X STACKER 3 HD tyre 18.00R33
MICHELIN X STACKER 3 HD 18.00R33
Since its launch, the MICHELIN X STACKER 3 HD energy efficiency and productivity performances are appreciated. For example, the Terminal du Grand Ouest (TGO) obtained 34% more wear performance than with their current tyres1. MICHELIN X STACKER 3 HD reaches the end of their service life on schedule, with no additional downtime. In short, the customer bought fewer tyres, with the machine covering more distance in an hour — the result: better productivity.
By selecting appropriate tyres and following proper maintenance practices, it is possible to reduce the risk of unscheduled maintenance and optimize uptime. Regularly checking tyre pressure and practicing safe driving habits can all be beneficial. Lastly, choosing the right product for the usage, vehicle, and terminal conditions can help extend tyre life, and save energy and costs. Michelin provides a wide range of products for reach stackers, such as the MICHELIN XZM 2+ / XZM 2+ tyre and MICHELIN X STACKER 2 tyre. For more information on our range of products, visit our port and terminals section.
1 Tests realized by the site's technical manager on a fleet of 10 reach stackers over a period of 3 years (2019-2023).
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