Chain conveyors—including scraper conveyors, apron conveyors, and inclined chain conveyors—are widely used in industries such as mining, port operations, building materials, and chemical processing, where they handle the continuous transport of heavy‑duty materials. At startup, the equipment must overcome both the static friction of the conveyed material and the inertia of the chain, subjecting the drive system to impact loads 2–3 times the rated torque, with peak inrush currents often exceeding the rated value by a factor of 3–5. Consequently, achieving smooth acceleration, mitigating chain‑induced shocks, balancing multi‑unit load distribution, and reducing maintenance costs are critical challenges in the design and retrofitting of chain conveyor drive systems.

I. Typical Challenges Faced by Chain Conveyor Drive Systems

In practical operation, chain conveyor drive systems often encounter the following issues:

The starting impact of heavy loads is significant. : The inrush current peak exceeds the rated value by 3–5 times, causing frequent motor trips and overloading the power distribution system.

Chain with severe impact damage : At startup, the enormous impact force is directly transmitted to the scraper chain, sprockets, and gearbox; in one coal enterprise, pin‑shaft fractures occur 2–3 times per month.

Overload, jamming, and motor burnout : When material accumulates, foreign objects become lodged, or the chain becomes jammed, the load can surge abruptly. Rigid couplings cannot provide any buffering, resulting in an extremely high risk of motor stalling and burnout.

Frequent start-stop operation accelerates wear. Under rigid transmission, impact is directly transmitted to each component of the drive chain, accelerating wear on the chain, sprockets, and gearbox gears.

Repeated oil leakage in dusty environments In industries such as building materials and cement, high ambient temperatures and heavy dust exposure accelerate the aging of seals, which, in severe cases, can lead to fusible plug rupture and production shutdowns.

Power imbalance in multi-motor drive systems : When the machine is driven by dual motors at both the head and tail, the “load‑sharing” issue is severe, with some motors operating under prolonged overload conditions.

II. The Role of the Hydraulic Coupler in Chain Conveyors

Hydraulic couplings transmit power via a liquid medium and possess inherently flexible transmission characteristics:

Soft start The motor starts nearly under no-load conditions, gradually accelerating the turbine via the hydraulic fluid and thereby reducing the peak inrush current.

Overload protection : Automatically slips to limit torque during sudden load changes, protecting the motor and gearbox.

Multi-machine balancing : By leveraging slip characteristics, each drive point proportionally shares the load.

Vibration damping and cushioning : Absorbs start-up shocks and operational vibrations, extending the service life of chains, sprockets, and gearboxes.

III. Coupling Solutions for ZTE Hydraulic Chain Conveyors

Guangdong Zhongxing Hydraulic Transmission Co., Ltd. (formerly established in 1958 and, since 1994, a joint venture with Germany’s Voith) has been deeply engaged in the hydraulic transmission field for decades, offering a comprehensive product lineup and customized solutions tailored to the operating conditions of chain conveyors.

Soft start with flexible control, eliminating electrical surges. : By adopting an extended rear auxiliary chamber design, the start-up time is extended to 22–30 seconds, and the peak inrush current is reduced to no more than 1.8 times the rated value.

Automatic load balancing, solving the challenges of multi-machine driving. By leveraging the slip characteristics of hydraulic couplings, each drive point proportionally and evenly shares the load, fundamentally mitigating the “load‑sharing” issue in multi‑motor drives.

Sensitivity‑limited torque protection ensures equipment safety. : Starting overload factor of 1.35–1.8, braking overload factor of 2–2.5; during overload, automatic slip‑limiting torque is engaged to protect the motor and gearbox from burnout.

High‑standard sealing and rapid maintenance : Designed to withstand high-temperature and dusty, harsh environments, the standard YOX series offers a maintenance-free interval of 6–12 months, while the upgraded DXA series extends this to 2–3 years. Featuring an external‑wheel drive configuration paired with an elastic sleeve‑pin coupling, it eliminates the need to relocate the motor and gearbox during disassembly, reducing single‑maintenance labor time by more than 60%.

IV. Application Cases

Retrofit of a 280 kW Chain Conveyor at a Coal Enterprise

The enterprise’s chain conveyor is equipped with a 280 kW, 750 r/min motor. During startup, the inrush current peaks at more than three times the rated value, causing frequent motor trips and resulting in chain pin‑shaft fractures occurring two to three times per month. After installing a YOXnz875 torque‑limiting hydraulic coupling, the peak inrush current was reduced from over three times the rated value to within 1.8 times, the chain’s impact load decreased by more than 60%, and pin‑shaft fracture incidents were completely eliminated. Moreover, the motor’s service life has been extended to more than twice its original duration. The transmission efficiency stands at 0.96, with an adjustable oil capacity ranging from 56 to 112 L, enabling flexible adjustment of output torque in response to load variations.

V. Key Considerations for Selecting Couplings for Chain Conveyors

Power and RPM Matching : Determine the transmission capacity based on motor power and rated speed. For chain conveyors, the typical power range is 200–600 kW, with speeds generally between 750 and 1,000 r/min. When selecting equipment, ensure that efficiency remains above 0.96.

Overload Factor Confirmation : The heavy-duty start-up scenario requires a starting overload factor of 1.5 to 1.8 times, and the braking condition must withstand peak torques of 2 to 2.5 times the rated value.

Startup Time Requirements For long-distance chain conveyors, it is recommended to select models with an extended rear auxiliary chamber; the start-up time should ideally be 22–30 seconds.

Ease of installation and maintenance : The design employs an external gear drive coupled with an elastic sleeve pin coupling, enabling disassembly without moving the motor or the reducer.

Oil charge adjustment : An appropriately sized oil fill ensures full utilization of the motor’s peak torque, enhances starting torque, and accommodates varying load characteristics.