How Does a Bag Conveyor with a Combustion Engine Work?

The mechanization of agricultural logistics has taken a significant step forward with bag conveyors powered by combustion engines. These machines, also known as sack conveyor belts, make it easier to move large volumes of bagged products (grains, fertilizers, seeds, etc.) quickly and efficiently. In Mexico, where many agricultural operations take place in rural areas without access to electricity, conveyors driven by gasoline or diesel engines provide a powerful, portable, and reliable solution. Below, we explore their operating mechanism, the types of engines used, their advantages over electric systems, operational efficiency, maintenance guidelines, and practical applications in hard-to-access rural areas, highlighting how they optimize agricultural logistics and reduce operating costs.

Operating Mechanism of a Bag Conveyor

A bag conveyor operates similarly to any industrial belt conveyor, with the key difference being that it uses an internal combustion engine instead of an electric motor. It consists of a robust metal frame that supports a continuous belt (typically made of reinforced rubber or PVC) tensioned around two rollers or pulleys. One of the rollers is driven by the engine, causing the belt to move forward and transport the bags placed on it.

Along the frame, there are idler rollers that support both the belt and the load, ensuring smooth movement. A tensioning system keeps the belt properly tightened, preventing slippage and ensuring that it remains centered. The speed (and in some cases the direction) of movement can be adjusted through the engine throttle or by changing gears, allowing adaptation to specific operational needs.

In simple terms, the operator places the sacks at one end of the conveyor (usually the lower end), and the engine drives the belt to carry the bags to the opposite end, which is typically elevated (for example, onto a truck bed or into a storage facility). Many designs incorporate sidewalls or guides along the belt to prevent sacks from slipping, as well as textured surfaces or V-shaped cleats on the belt to improve grip on inclined runs. In addition, these conveyors are often adjustable in height and inclination, using hand cranks, simple hydraulic systems, or mechanical jacks, allowing alignment with a truck edge or the top of a stack of bags. In summary, the mechanism combines a mechanical engine, a transmission system (belts or chains), and the belt-and-roller assembly to achieve a continuous, efficient, and controlled flow of sacks from point A to point B.

Types of Combustion Engines Used

Portable bag conveyors typically use four-stroke internal combustion engines, commonly found in small agricultural equipment. Gasoline engines are most widely used due to their availability and lighter weight, although diesel engines are also offered in higher-power models. Typical power ratings vary depending on conveyor size and expected load: models are available with engines starting at around 6.5 HP (approximately 196 cc gasoline engines) and extending to industrial engines of 10 HP or more.

Internal Combustion Engine

For example, a certain Mexican conveyor belt measuring 7.5 meters in length and 75 cm in width is equipped with a 10-horsepower gasoline or diesel engine to drive the belt while carrying heavy sacks. These engines generally feature a manual recoil starter (pull cord)—similar to those used on water pumps or generators—and a throttle to regulate RPMs and, consequently, belt speed.

The engine is coupled to the drive drum of the belt through a transmission system, which may include V-belt pulleys, chain-and-sprocket assemblies, or a gear reducer. This system reduces the high engine speed to an appropriate operating speed, providing sufficient torque to lift sacks weighing 50 kg or more. Some advanced models incorporate centrifugal clutches or tensioners that prevent belt movement at idle and allow the engine to start without load. Regarding fuel, gasoline is common due to its easy availability in rural communities; diesel, on the other hand, offers higher torque at low RPM and better fuel efficiency for prolonged operation, making it ideal where robustness is required and diesel is available (for example, on ranches with heavy machinery). There are also versatile designs in which the same conveyor can be ordered with an electric motor, gasoline engine, diesel engine, or even adapted to a tractor power take-off (PTO), depending on user preference. This flexibility ensures that the conveyor integrates seamlessly into different agricultural setups.

Advantages Compared to Electric Systems

Why choose a combustion engine instead of an electric motor? The answer usually lies in portability and autonomy. In the Mexican agribusiness sector, many crop fields, farms, and collection centers are located in areas without immediate access to the electrical grid. In fact, more than 4,473 rural communities in Mexico lacked electrical service as of 2025. In these environments, a conveyor belt powered by a gasoline or diesel engine can operate anywhere and at any time, without relying on generators or grid connections. This contrasts with electric conveyors, which—although efficient—would require at least a portable generator, cables, and plugs, adding logistical complexity.

Specific advantages of combustion-engine-powered conveyors include:

Total mobility:They are typically mounted on large pneumatic wheels (for example, R13 automotive tires) and equipped with a ball-type towing hitch. This allows them to be easily towed by pickup trucks, tractors, or ATVs to crop fields or between warehouses, covering the “last mile” in difficult terrain. A single operator can move and position the unit thanks to an integrated manual steering handle. All of this would be far more complicated with equipment dependent on fixed electrical cables.

Independent power:A combustion engine provides high torque to the belt without concerns about voltage drops. Three-phase electric motors require a stable electrical installation; in contrast, a gasoline engine only needs fuel to deliver its rated power. This makes it ideal for heavy loading tasks that demand several horsepower continuously.

Versatility for outdoor use:Combustion-powered conveyors can operate under light rain or in humid environments without the immediate risk of short circuits (although excessive water exposure to the engine should be avoided). They do not require expensive waterproof wiring and can be positioned in the middle of a field, at the base of a silo, or next to a harvester with minimal preparation—just fuel the tank and ensure stable ground positioning.

Quick start-up:A modern combustion engine can be started in seconds using the pull starter or an electric start system (available on some Honda models). There is no need to wait for installations; even during a power outage at a processing plant, a gasoline-powered conveyor can continue operating and prevent interruptions.

It is fair to note that electric systems offer lower noise levels and zero point-of-use emissions, which is important in enclosed warehouses. However, in open rural settings, the noise from a small gasoline engine is generally acceptable, and emissions dissipate outdoors. Additionally, farmers are usually familiar with maintaining gasoline engines (similar to water pumps or chainsaws), whereas electric motors may require specialized technical support if they fail. In short, energy independence and mobility make combustion-engine conveyors stand out for remote or mobile agricultural applications.

Operational Efficiency and Logistics Optimization

Implementing a bag conveyor can completely transform logistics on an agricultural operation. These machines speed up the movement of large product volumes with minimal human effort, dramatically increasing productivity. For example, well-adjusted sack conveyors can reach transport speeds of up to approximately 24 sacks per minute (for 25–50 kg sacks) during bagging and loading operations. This is equivalent to moving more than 70 metric tons of goods per hour—something virtually impossible to achieve with manual labor without enormous cost and physical strain.

Logistics optimization is reflected in several concrete aspects:

Fewer bottlenecks:During harvest, time is critical. A conveyor allows continuous loading of trucks or stacking of sacks in warehouses, preventing delays. There is no longer a need for manual sack-by-sack handoffs, which are slow and error-prone. The conveyor creates a steady flow of sacks that can be managed by just two workers—one feeding the belt at the bottom and one receiving and stacking at the top.

Reduced labor and operating costs:By mechanizing loading, the need for day laborers in repetitive tasks is reduced. A team of 2–3 people with a conveyor can complete in minutes what previously required large crews working for hours. This lowers wage costs and frees personnel for higher-value activities. As industry experience shows, conveyors allow large volumes (grains, sacks, boxes, etc.) to be moved in less time and with less effort, reducing operating costs and increasing productivity.

Less product damage and improved ergonomics:Traditional sack handling involves lifting, throwing, or dropping bags, which can break packaging and waste product. Conveyors transport sacks smoothly, minimizing impacts and preserving product integrity. Workers avoid continuously lifting heavy loads, reducing muscular injuries and improving workplace safety. In simple terms, the work becomes safer and less exhausting, resulting in lower absenteeism and a more motivated workforce.

Fast return on investment (ROI):Although acquiring a conveyor is an investment, savings in labor hours and faster dispatch operations typically pay for the equipment in a short time. With relatively low fuel consumption and simple maintenance requirements, operating costs remain low. Many companies report a guaranteed ROI due to the combination of reduced labor costs, higher daily throughput, and improved product handling.

Practical example:Imagine a corn-growing community in Chiapas during harvest season. Previously, loading a truck with 200 sacks of 50 kg corn could take several hours with 6–8 workers using planks. Now, with a portable conveyor, two operators complete the task in a fraction of the time: one feeds the sacks onto the belt while the other stacks them on the truck. In less than an hour, all 200 sacks can be loaded—a task that might otherwise take half a day manually. This increased speed allows more trucks to be dispatched per day, reducing freight costs and ensuring corn reaches the market fresher. At the same time, physical strain is greatly reduced, lowering fatigue and injury risk. Overall, harvest logistics are optimized, meeting tighter delivery schedules and avoiding bottlenecks during peak demand.

Maintenance and Care of the Conveyor

To ensure safe operation and extend the service life of the conveyor, regular maintenance of both the mechanical belt system and the engine is essential. Key maintenance practices include:

Periodic inspections:Before each workday, visually inspect the belt for wear, cuts, or damaged splices. Check alignment—the belt should run centered on the rollers without drifting. If misalignment is observed, adjust the tension rollers or drum alignment bolts to correct it, as sustained misalignment can damage belt edges. Also verify proper belt tension—neither too loose (which may cause slipping) nor overly tight (which can overheat the engine and accelerate wear).

Regular cleaning:After intensive use, clean accumulated material (soil, grain, fertilizer dust) from rollers, drums, and the engine base. Dirt buildup can cause slippage and accelerated wear. Periodic cleaning of the transmission system and rollers prevents premature damage and maintains efficiency. Wiping down the belt to remove embedded residues helps prevent cuts and deterioration.

Lubrication and moving parts:Roller and drum bearings are often sealed, but if not, they should be lubricated according to manufacturer recommendations (typically grease every set number of operating hours). Chains or gear transmissions should also be checked and lubricated to reduce friction. Avoid over-lubricating the belt itself, as oil or grease can make it slippery for sacks.

Engine maintenance:Treat the combustion engine like any small engine: change oil at recommended intervals (typically every 50 operating hours), inspect and clean or replace the air filter (especially important in dusty environments), and periodically check the spark plug for optimal combustion. Use clean fuel, and in diesel engines, regularly purge the fuel filter to prevent clogging. During operation, watch for unusual noises or vibrations, which may indicate bearing issues, misalignment, or loose components.

Safety components:Ensure that guards and covers for moving parts (pulleys, chains, engine fan) are in place to prevent accidents. Check the condition of wheel brakes or chocks, if equipped, to immobilize the conveyor during operation. Some advanced models include safety switches or emergency stop sensors—test them periodically to ensure proper function.

Keeping a maintenance log helps ensure these tasks are not overlooked. Proper adjustment, cleaning, and lubrication minimize the risk of unexpected downtime. Preventive maintenance is critical, as equipment failure during peak harvest season can be costly. Finally, storing the equipment under cover when not in use protects it from sun and rain, preventing belt degradation and engine corrosion.

Applications in Rural and Hard-to-Access Areas

Combustion-engine-powered conveyors excel in remote rural environments or difficult terrain where conventional electric equipment would be impractical. Typical applications in Mexico include:

Harvesting in remote fields:In regions such as the Sierra of Puebla or agricultural communities in Oaxaca, coffee, corn, and bean producers work in plots far from the electrical grid. After harvest, grains are often bagged in 50–60 kg jute or polypropylene sacks. A gasoline-powered portable conveyor allows these sacks to be moved uphill or downhill on slopes or across uneven terrain to collection trucks—without electricity. For example, coffee farms in Chiapas commonly use conveyors to transfer sacks of parchment coffee from hillsides to trucks, greatly easing a task that once required workers to carry heavy loads on their backs.

Storage in rural warehouses:Many rural grain silos or storage facilities lack fixed lifting systems. With a conveyor, a single operator can bring the machine to the warehouse entrance and elevate sacks to mezzanine levels or high shelving. This has proven useful in community corn and wheat warehouses in the Bajío region, where the conveyor is shared among farmers to stack sacks after harvest. Adjustable height (typically lifting 3–4 meters) allows rapid formation of stacked walls of sacks, making better use of vertical space.

Operations in areas without infrastructure:In government fertilizer distribution programs in Guerrero or Chiapas, delivering electricity to every distribution point is impractical. A diesel-powered conveyor can unload entire truckloads of fertilizer in minutes directly at community centers, speeding distribution and reducing physical effort for farmers. Similarly, in agave cultivation (Jalisco, Nayarit), specialized conveyors are used to move agave offshoots and harvested piñas across volcanic terrain where other machinery cannot operate. A 9-meter-long, 20-inch-wide conveyor with a combustion engine has proven effective in transferring agave offshoots to trailers without damage, thanks to its sidewalls that prevent falls.

Use in natural disasters or emergency situations:Although not their primary application, these conveyors can support temporary logistics operations—such as moving sandbags to build flood barriers or loading bagged humanitarian aid in areas where electrical infrastructure has been damaged. Their independence makes them valuable tools for on-the-ground response.

In all these cases, the common factor is the conveyor’s independence and adaptability. It can reach the “last mile” where sack transport is needed, navigating dirt roads, slopes, or tight farm spaces. Its robust carbon steel construction, all-terrain tires, and protected engine allow operation under sun, dust, and rugged conditions. This opens opportunities to improve efficiency not only in large agribusinesses but also in smallholder operations, reducing physical hardship and modernizing traditional processes.

Impact on Agricultural Logistics and Cost Reduction

The adoption of combustion-engine bag conveyors in Mexican agribusiness is optimizing logistics comprehensively. When viewed holistically, several positive economic and operational impacts emerge:

Accelerated supply chain:The speed at which products move from field to truck and from truck to warehouse or processing plant shortens logistics cycles. Agricultural products reach markets fresher and faster. In the sugar industry, for example, bagasse and other bagged by-products can be evacuated immediately using conveyors, freeing space and keeping plants running without interruption. Commercial farms can meet delivery contracts more quickly, building customer trust through punctuality.

Lower ongoing operating costs:Beyond labor savings, these conveyors typically have low operating costs. Hourly fuel consumption is relatively small compared to the volume moved, and preventive maintenance is simple and inexpensive (oil, filters, generic parts). Specialized industry sources note that well-designed conveyors are energy-efficient and low-maintenance, optimizing resources and delivering high performance over many years. In terms of cost per ton moved, conveyors are highly competitive compared to manual alternatives.

Increased productive capacity without major infrastructure investment:Traditionally, some producers invested in forklifts or hydraulic loaders to speed loading—equipment that is expensive and requires specialized fuel and maintenance. A conveyor is a more economical and versatile solution for a certain operational scale. While it cannot replace a forklift in all tasks, it is unmatched in cost-benefit for moving sacks. Many mid-sized agribusinesses have found conveyors to be an effective way to professionalize logistics without excessive debt.

Improved quality and reduced losses:By minimizing damage to sacks and contents, losses from broken or contaminated products are reduced. A sack dropped from a truck may rupture and spill contents; conveyors prevent this. For sensitive products (e.g., certified seed or compound feed), this preserves quality and value, avoiding replacement costs. Indirectly, the company’s commercial image improves by delivering products in good condition and on schedule.

Sustainability and worker well-being:From a broader perspective, mechanizing heavy labor contributes to the human sustainability of agriculture. Workers can focus on supervision, quality control, or other tasks while the conveyor handles heavy mechanical work. This reduces physical strain and can improve worker retention in communities where young labor often migrates in search of better conditions. Safer, more efficient working environments also reduce injuries and enhance the perception of agriculture as a modern, technology-driven activity.

Combustion-engine-powered bag conveyors have become a strategic tool for agricultural logistics in Mexico. They combine simple yet effective engineering—a moving belt driven by a reliable engine—with a design tailored to real field conditions. Their continuous operating mechanism, ability to function anywhere, and multiple operational and economic advantages make them indispensable for any agroindustrial operation handling significant volumes of bagged products. Companies and producers that have adopted these conveyors report significant productivity gains and reduced operating costs, confirming that they are a rapidly recoverable investment. In a sector where competitiveness and efficiency are increasingly critical, equipment like combustion-powered conveyors can make the difference between traditional logistics and a truly optimized operation—representing a clear step toward the modernization and sustainability of Mexican agriculture in the 21st century.