Why Apron Feeder Start Up During High Load

High-load startup refers to situations where the equipment starts while already carrying a large amount of material or load, or when material adhesion, equipment blockage, and other issues cause resistance far beyond normal levels. Worn components or inadequate lubrication can also lead to excessive load during startup.

In practice, high-load startup is very common, often causing severe damage to ordinary conveying equipment.

However, for Apron Feeders, high-load startup has better solutions. Widely used in mining, metallurgy, building materials, and coal industries, Apron feeders are mainly designed to evenly and continuously deliver large, heavy-impact materials to the next stage of crushing, screening, or conveying.

With heavy-duty design, proper motor selection, and soft-start technology, Apron feeders minimize the negative effects of high-load startup, thereby extending service life. This article explains in detail how Apron feeders handle such working conditions.

Potential Impacts of High-Load Startup

Motor Overheating

For ordinary motors, the inrush current at startup is usually 5–8 times the rated current. High-load startup amplifies this value, generating huge heat in the windings in a short time. If the temperature exceeds insulation tolerance, it accelerates insulation aging, short-circuiting, or even motor burnout.

Component Damage or Loosening

High-load startup subjects gears, bearings, and belts to torque and tension far beyond their design values. For example, if the startup torque of a gearbox exceeds 1.5 times its rated value, it may cause surface wear or broken teeth. Bearings may crack or deform under impact loads. In addition, the vibration is much stronger than during normal operation, which can loosen bolts and other parts.

Fatigue Damage

High-load startup is a typical “impact load.” Metal structures and electronic components are exposed to repeated instantaneous stresses, leading to fatigue damage. For instance, a motor rotor shaft under frequent excessive torque may develop microcracks, which grow into fractures over time.

Excessive Energy Consumption

During high-load startup, energy conversion efficiency drops significantly. The power factor of the motor decreases, resulting in much higher electricity consumption. Unstable operation during startup may also cause fluctuations in material output, reducing production accuracy.

Safety Risks

In dusty or flammable environments, overheating motors may lead to fire hazards. Damaged or loose components may cause sudden shutdowns, posing risks to operators.

How Apron Feeder Handles High-Load Startup

Heavy-Duty Structural Design

The frame adopts an I-beam design with stiffeners welded between upper and lower flanges, which effectively disperses impact forces and enhances load-bearing capacity. During high-load startup, this helps distribute enormous instantaneous stress.

The buffer rails absorb material impact, sharing startup stress and energy, reducing force on pans and chains, and extending their service life.

Drive System

The variable frequency motor is connected to the reducer through a coupling and uses a VFD for soft start. Even under a heavy-load startup, the feeder can accelerate gradually, minimizing impact.

The P2K series planetary gearbox features an involute planetary gear transmission, with a total reduction ratio of 225:1. Input speed is 1475 rpm, rated transmission power is 128 kW, and output speed is 14.5 rpm. This design splits power effectively, ensuring smooth and reliable operation.

Pans

Made of high-manganese steel castings or reinforced welded structures, resistant to strong impact. The single-arc overlapping design prevents leakage, distributes material weight, and extends service life.

Chains

Bulldozer-type crawler chains, with high strength, large tensile force, minimal pitch error, and self-lubrication. Service life can last for decades without replacement.

Soft Start

Through VFD control, motor speed increases gradually from 0 to rated speed, avoiding full-load shock at startup. This reduces torque impact on chains, gears, and drive components.

Operating Strategies for High-Load Conditions

Load Monitoring

Equipped with a speed switch to monitor operating speed in real time. If abnormalities occur, a signal is triggered and the protection system stops the machine automatically. Motor temperature sensors prevent overheating and burnout.

Soft Start Control

The VFD converts AC power into DC, then into AC with adjustable frequency and voltage, thereby shifting the motor’s operating curve. This allows the motor to start with a smaller current while achieving larger startup torque. As a result, Apron feeders can smoothly start even under full or heavy loads, minimizing system impact.

Maintenance During High-Load Operation

Lubrication

Only the reducer, sprocket shaft assembly, carrying rollers, and tensioning device require lubrication, typically every six months. Most components are sealed against dust and water, extending lubrication intervals. Chains and roller bearings are self-lubricating, providing longer service life.

Discharge Opening Distance

The distance between the discharge opening and pans must be at least 1.5–2 times the maximum lump size of the material. Otherwise, material may accumulate, affecting stable conveying.

Chain Wear

Although durable, chain pitch wear must be controlled within 7 mm. If exceeded, the chain should be replaced promptly.

Component Inspection

Before the operation, check the chain tension, trough straightness, and bolt tightness. Replace worn parts or tighten loose bolts immediately if abnormalities are found.

The ability of Apron feeders to start smoothly under high load lies in their robust structural design, advanced drive system, heavy-duty pans and chains, and VFD soft-start technology. These features effectively reduce startup impact on motors, chains, and gears, ensuring long-term reliable operation.

With load monitoring and proper maintenance strategies, Apron feeders remain durable and efficient even in demanding environments like coal mining, metallurgy, and building materials.

For industries handling large, heavy-impact materials, Apron feeders not only reduce failure rates and downtime but also save operating and maintenance costs, making them one of the most reliable heavy-duty conveying solutions available.