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Quick answer: A custom crawler undercarriage for a Chilean orchard harvester combined a 400 mm rubber track, an extended track frame and a 210 kg weight reduction, taking ground pressure from 59.7 to 36.5 kPa. Rows lost to sinkage fell from 14 percent of the block to 2 percent.
In the Chilean apple and pear growing regions of Maule and O'Higgins, a harvest-season window of roughly five weeks determines the entire economics of the year. A harvester that cannot work a wet row does not come back to it the following day, because the window closes. It works a different row, or not at all.
That is the context in which a harvester OEM approached MAGEON in 2024 with a problem that looked, on paper, like a routine component complaint.
The customer's position
The OEM builds a self-propelled orchard harvester with a 4.2-tonne operating weight, working in high-density apple orchards on slopes of 8 to 15 degrees, on ground that is soft after irrigation and rain. The machine was losing ground badly in the wet part of the season.
Two specific consequences were reported:
- Sinkage and stalling. In the wet weeks, the machine sank to the axle in a proportion of the rows, and the operator had to wait for the ground to dry or move to a different block. The operator described a machine that "works well until the soil is wet, and then it stops being a machine and becomes a boat".
- Crop damage. Steel tracks on wet orchard soil were damaging the root zone and the irrigation lines, and the grower was charging the damage back against the harvest contract.
Both problems were, at their core, the same problem expressed in two ways: too much ground pressure for the ground.
Baseline measurement
Before proposing anything, we asked the customer to supply the machine's actual working weight and the track configuration, and then we calculated the ground pressure of the existing arrangement:
| Parameter | Existing configuration |
|---|---|
| Machine operating weight | 4,200 kg |
| Track configuration | Steel, 300 mm shoe, 1,150 mm contact length |
| Total contact area | 0.69 m² |
| Calculated ground pressure | 59.7 kPa |
For reference, the bearing capacity of the clay-loam orchard soils in that region during the wet season is typically 45 to 70 kPa. The machine was operating at or beyond the ground's capacity, which is precisely the condition in which bearing failure and sinkage occur.
Our target was to bring the ground pressure below 30 kPa, giving a margin of more than 1.5 times against the wet-season bearing capacity.
The design
The constraint the customer imposed was that the machine could not change its external dimensions: the harvester's body, the bin position, and the orchard clearance were all fixed, and the harvester had to fit between existing rows.
Our solution combined three changes:
| Change | Detail | Effect |
|---|---|---|
| Rubber track, 400 mm shoe | Wide-pad rubber track, 400 mm | Contact area up, contact spread over the full pad rather than grouser lines |
| Extended track frame | Track length increased, with a longer hydraulic tensioner stroke to maintain contact over the greater span | Contact length up from 1,150 mm to 1,340 mm |
| Reduced undercarriage weight | Optimised frame section and roller train, offset by a higher-strength steel grade | Machine operating weight down 210 kg |
Resulting figures
New contact area = 2 × 1.34 × 0.40 = 1.072 m²
New operating weight = 4,200 − 210 = 3,990 kg
New ground pressure = 3,990 × 9.81 ÷ 1.072 = 36.5 kPa
With the additional contribution from the rubber pad's contact behaviour in soft soil, the effective figure in the field measured lower still. The improvement against the original 59.7 kPa is 39% in calculated terms, and the field measurement — taken with a penetrometer at the depth of the track contact patch — showed a 58% reduction in the soil's measured bearing stress beneath the machine.
Field results across two harvest seasons
The customer ran the revised machine over the 2024-25 and 2025-26 seasons and provided the following data against the previous configuration:
- Rows lost to sinkage: 14% of the block in the wet season, down to 2%. The remaining 2% was in the two lowest blocks and was accepted.
- Crop damage claims from growers: effectively eliminated; the grower association confirmed the change across the whole cooperative.
- Season length actually worked: extended by approximately 9 days, because the machine was no longer waiting for dry rows. On a 40-day harvest window, that is a 22% increase in effective harvest capacity.
- Noise: the operator reported the machine being "much easier to be in for a long shift", which the customer noted had improved driver retention on a machine that had previously been hard to staff.
Why the extended frame mattered as much as the rubber
It would be easy to assume the rubber track did all the work. It did not. The extended track frame contributed roughly 17% of the area increase, and it did something the rubber could not: it kept the track in contact over a longer span, which meant the machine's weight was distributed rather than concentrated, and the machine presented a longer, shallower angle to the soil as it pushed through it.
This is the bulldozing effect. A machine moving through soft soil is resisted by the soil in front of the track as much as by its own ground pressure. Extending the contact length reduces the bulldozing resistance in a way that widening alone does not, because the displaced soil is spread over a longer, shallower wedge.
The manufacturing and commercial detail
Two points that often matter more than the engineering:
Delivery. The customer needed the first chassis within the same season, not the next one. MAGEON produced the first unit in 32 days from drawing sign-off and held a rolling delivery schedule for the remaining units against the customer's own assembly plan.
Change control. The extended frame required a modified mounting interface, because the roller group positions moved. This was resolved by keeping the machine-side interface unchanged and the chassis-side adjustment internal, so the customer's existing assembly fixtures and jigs remained valid. On a production machine, preserving the customer's fixtures is often worth more than the design freedom to optimise.
Broader outcome
The revised chassis was not sold as a specialty item. After the first two seasons, the OEM standardised the low ground pressure configuration across its entire orchard harvester range, and the configuration was subsequently adapted for two further fruit-harvester models in the same region and one nut-harvester model in a different soil type.
What started as a complaint about one machine in one block became a platform-level decision for a product line.
MAGEON product lines and how they map to this topic
The engineering principles in this article apply across the full MAGEON product range. Each custom undercarriage order starts from one of four chassis families, and the selection logic above determines which one fits your machine.
| MAGEON product line | Typical tonnage | Best suited to |
|---|---|---|
| Customized steel track chassis | 3-60 T | Quarry, mining, crushing, demolition, heavy lifting and drilling rigs, where abrasive rock and impact loading drive the wear pattern |
| Customized rubber track chassis | 0.5-30 T | Urban construction, utility trenching, landscaping, agriculture and any finished-surface work where noise, surface protection and low ground pressure matter |
| Customized steel track undercarriage | 5-120 T | Continuous-duty mining and screening plant, large crawler cranes and heavy equipment carriers running extended shifts in abrasive conditions |
| Customized rubber track undercarriage | 1-20 T | Compact and mini excavators, tracked dumpers, harvesters and municipal plant, where a custom undercarriage is specified to meet ground pressure and noise requirements on the same machine |
Whether you are specifying a custom undercarriage from first principles, comparing a customized steel track chassis against a customized rubber track chassis, or reviewing the service life of a customized steel track undercarriage in abrasive service, MAGEON can size, engineer and support the build. Every crawler undercarriage project begins with your machine's weight distribution, working conditions and interface drawing, and the quotation is backed by a written calculation. Contact our engineering team with your host model, working conditions and mounting interface, and we will respond with a configuration recommendation within one working day.