Praxis der Staplerauswahl: Sieben-Dimensionen-Vergleich mit Rädern und Armen und fünf Auswahlfalle

When a large power plant in the south expanded its coal yard, there was a heated debate on equipment selection. One side insisted on choosing the mature technologyBoom type stacker reclaimerThe other side pushed for a more flexible wheeled stacker reclaimer. The debate went on for three months, and finally the power plant’s deputy chief engineer, Lao Chen, snapped, “Let’s go and look at real-life examples before we say anything.” They visited six power plants and harbours using different types of stacker reclaimer, and found many details that wouldn’t be in the technical manuals.

Behind this debate is the classic problem of stacker reclaimer selection that has plagued countless project engineers. Choose the right one, the next ten years of operation smoothly; choose the wrong one, every day is trouble.

First, the essence of the working principle of the difference: not “wheels” and “arm” so simple
Many people think that a wheeled stacker is one with wheels, and an arm is one with a cantilever. This understanding is too superficial. The core difference between the two lies in the material flow control logic.

The working logic of boom type stacker reclaimer (commonly known as cantilever type) is “fixed point stacking, mobile compensation”. The front end of the cantilever is the fixed working point, and the stacking and reclaiming operation is completed by cantilever pitching and rotating, and the whole machine travelling is only adjusting the working position. This is just like a person working with a shovel in a fixed position, and walking over when he needs to change the position.

Real data from a port in Guangdong: when their boom stacker reclaimer is stacking coal, the whole machine needs to be moved only once every 8-10 hours, during which the cantilever completes all the fabric operations. This mode of operation is characterised by high precision (±150mm error at the drop point), but the coverage is limited by the length of the cantilever.

The working logic of wheeled stacker reclaimer (gantry type, bridge type, etc.) is “mobile stacking and reclaiming, continuous operation”. Its reclaimer moves horizontally on the gantry, and the whole machine travels longitudinally along the track, forming a two-dimensional work plane. It is like a person pushing a shopping trolley between the shelves to pick up goods.

Comparison test of a steel mill in Hebei showed that: in the 120-metre-long yard, the wheeled stacker reclaimer to complete the full area of the reclaimed material faster than the arm type 35%, but the amount of reclaimed material per unit of time fluctuates greatly.

II. The truth about site suitability: the data don’t lie
We tallied actual operational data from 47 domestic stacker reclaimer projects and found some counter-intuitive conclusions:

Feedlot length in relation to selection:

Yard length <80 metres: economic advantage of the boom type

80-150 metres: each has its own advantages and needs to be assessed in a comprehensive manner

>150 metres: wheeled for better overall efficiency

But this conclusion has an important premise – the shape of the pile. If the shape of the pile needs to be changed frequently (e.g., multi-variety stacking), the arm type can be adjusted faster than the wheel type because of the flexibility of the cantilever, which is more than 40%.

Differences in foundation requirements:
A seaside power plant in Fujian had ignored this problem and installed a wheeled stacker reclaimer on a soft foundation. As a result, the track settled unevenly and the track foundation was repaired three times in two years, with the total cost exceeding 15% of the equipment’s payment. whereas the boom type has relatively low requirements for the track because its main load is transferred to the central area of the foundation through the centre column.

Empirical formula: Wheeled stacker reclaimer requires ≤1/1000 for track flatness, boom type can be relaxed to ≤1.5/1000.

III. The complete book of investment costs: don’t just look at the purchase price
The purchase price is just the tip of the iceberg. The cost analysis of a mining company in Inner Mongolia is illustrative:

They purchased a boom stacker reclaimer (purchase price $8.2 million) and a wheeled (purchase price $6.8 million) to compare the total five-year costs:

Arm stacker reclaimer:

Procurement cost: $8.2 million

Foundation construction: $1.2 million (large concrete foundation required)

Five-year energy consumption: $930,000 (average power 185kW)

Maintenance costs: $0.67 million (including two major repairs)

Total cost over five years: $11 million

Wheeled stacker reclaimer:

Procurement cost: $6.8 million

Foundation construction: $1.9 million (full-length high-standard track required)

Five-year energy consumption: $1.28 million (average power of 255 kW, high mobile energy consumption)

Maintenance cost: $1.05 million (high failure rate of travelling mechanism)

Total cost over five years: $11.03 million

Amazingly, the total five-year cost of both is almost the same! But the equipment supervisor told me, “You can’t do the maths like that, the boom’s capacity utilisation is 18% higher than the wheeled, and that’s the key.”

IV. Realistic Considerations of Maintenance Complexity: Voices of Maintenance Teams
Whether the equipment is good or not, the maintenance team has the most to say. Lao Li, the maintenance team leader of a cement plant in Shandong, who also maintains two boom and one wheeled stacker reclaimer, has a very intuitive comparison:

“The main repairs on the jib are in the slewing bearings and cantilever hinge points. Last month we repaired the slewing bearings and it cost us $21,000 for a two-day job by three people. The main problems with the wheeled type are in the travelling wheelset and the deflection correction device. The deflection correction device has to be adjusted every month, and although it only takes half a day each time, it is too frequent and affects production.”

Comparison of failure rate data (annual failure downtime):

Boom stacker reclaimer: average 120-180 hours/year

Wheeled stacker reclaimer: average 180-260 hours/year

But Lao Li added an important point: “Wheeled breakdowns are well handled, and most can be repaired on the track. The jib type has to be scaffolded if the cantilever hydraulics go wrong, which is more troublesome.”

V. Key indicators of operational efficiency: empirical data to overturn perceptions
A six-month comparative test was carried out at a port in Jiangsu province, where boom and wheeled stacker reclaimers were installed at adjacent locations in the same yard, handling the same type of coal:

Stacking capacity:

Boom: 1350 tonnes/hour average (limited by cantilever slewing speed)

Wheeled: average 1620 tonnes/hour (continuous walking stockpile)

Pick-up capacity:

Arm: 980 tonnes/hour average (fixed cross-section of reclaim head)

Wheeled: average 1150 tonnes/hour (large reclaimer width)

Does it look like the wheeled type is winning? But the deputy director of the port’s technical department points out the key problem: “The wheeled type is not as good as the boom type in terms of reclaim uniformity, leading to frequent overload protection trips on subsequent belt conveyors. Taking this effect into account, the actual effective reclaim capacity is about the same for both.”

VI. Space for future transformation and upgrading: room for intelligence
Selecting equipment now must take into account future intelligent upgrades. The two models have different bases for intelligent upgrading:

Boom stacker reclaimer retrofit focus:

Addition of cantilever end vision system for automatic stacking control

Upgraded rotary encoder accuracy from ±0.1° to ±0.02

Retrofitting of material flow monitors

Wheeled stacker reclaimer retrofit focus:

Additional position reference points in the track for centimetre-level positioning

Condition monitoring sensors added to travelling wheelsets

Automated upgrade of the deflection correction system

The transformation case of a Shanxi power plant shows that: the boom type stacker reclaimer to achieve semi-automatic transformation investment of about 450,000 yuan, wheeled need 680,000 yuan. However, after the transformation, the wheeled type in unattended operation hours than the arm type more than 30%.

VII. Checklist for selection decisions
Based on the 31 selection cases we have tracked, we have summarised seven issues that must be clarified before selection:

Material properties: What is the angle of repose? What is the fluidity? Is it sticky? (Wheeling should be used with caution for viscous materials)

Yard planning: will yard layouts change in the next five years? (Wheeled poorly adapted to layout changes)

Climatic conditions: increased maintenance of wheeled tracks in rainy areas over 50%

O&M team: which models are the existing team familiar with? (Training costs to be considered)

Capacity fluctuations: how much does seasonal or cyclical capacity vary? (Wheeling is more adaptable to capacity fluctuations)

Spare parts availability: Is there a reliable local supplier of spare parts?

Expansion plans: Is there a need to add a blending function in the future? (arm type is easier to add a mixing unit)

Final recommendation: organise a selection team of 5-7 people, including process, equipment, civil, electrical and purchasing professionals. Spend a week on site visits to at least three different types of user sites, and talk to operators, maintenance workers, equipment managers. Their practical experience is more valuable than any product samples. Remember, there is no such thing as the best equipment, only the most suitable equipment.