A harvester is a machine that harvests crops in one go. It completes harvesting and threshing at one time, and collects the grains into storage bins, and then transports the grains to transport vehicles via conveyor belts. It can also be harvested manually, with rice, wheat and other crops’ straw spread out in the field, and then picked up and threshed by grain harvesters. Crop harvesters harvest grains and straws of cereal crops such as rice and wheat. It includes harvesters, reapers, balers, grain combine harvesters and grain threshers.
1. Classification of harvesters
Harvesters include side-mounted harvesters, backpack harvesters, walk-behind harvesters, and suspended harvesters.
- Side-mounted harvester
The side-mounted harvester adopts a hard shaft transmission , which is mainly composed of an engine, a transmission system, a clutch, working parts, an operating device and a side-mounted belt. A 0.75-2 kW single-cylinder two-stroke air-cooled gasoline engine and a centrifugal friction clutch are configured at one end of the transmission shaft , and a working part consisting of a reducer and a cutting tool is installed at the other end. There are many types of working parts, and circular saw blades, blades or nylon wires are commonly used. When operating, hang the hook ring on the aluminum alloy sleeve of the transmission shaft on the shoulder strap under the operator's shoulder , hold the handle, and swing the hard shaft horizontally to complete the operation of cutting weeds, shrubs, etc. The machine weighs about 6 to 12 kg and has a speed of about 4500 to 5000 rpm.
- Backpack harvester
The backpack harvester uses a flexible shaft drive. The general structure is similar to the side-mounted brush cutter. The difference is that the engine is carried on the operator's back, and the cutting parts are driven by a flexible shaft. The engine power is generally 0.75 to 1.2 kilowatts. The engine and the back frame are connected at two points and equipped with special rubber parts for vibration isolation. The flexible shaft is a steel wire flexible shaft set in a hose to transmit torque. The hose is a threaded tube wrapped with a metal braided mesh covered with a rubber protective sleeve to prevent dust from invading the shaft and keep the lubricating oil on the shaft surface. The cutting width is generally between 1.5 and 2 meters.
- Walk-behind harvester
The walking-type harvester is supported by the walking wheels, and the machine is pushed forward by people, and the engine drives the working parts to perform cutting and brushing operations. Its structure and working principle are similar to those of portable brush cutters. The hanging harvester is hung behind the tractor, and the working parts are driven to rotate by the power output shaft. It is suitable for large-scale brush cutting operations . It is mainly composed of a frame, a saw blade, a transmission device, a suspension device and a push plate. During brush cutting operations , the tractor moves backwards, the working speed is 5 km/h, and the bushes with a diameter of 10 cm can be cut.
- Horizontal harvester
The horizontal harvester consists of a reel , one or two canvas conveyor belts, a straw divider , a cutter and a transmission device. During operation, the reciprocating cutter, in cooperation with the reel pressure plate, cuts the crop and pushes it backward onto the canvas conveyor belt, which then delivers the crop to the left side of the machine. Since the rear conveyor belt of the double conveyor belt is longer than the front conveyor belt, the ear head part falls to the ground later, and the discharged straw is laid on the ground in a neat strip at an angle to the direction of the machine, which is convenient for manual picking and bundling. The horizontal harvester with a header has good adaptability to different growth densities, plant heights, lodging degrees, and yields of rice and wheat, and has a simple structure; however, the longitudinal dimensions are large, and the flexibility of the unit is poor during operation. It is mostly equipped with wheeled or walking tractors below 15 kilowatts, and the cutting width is less than 2.0 meters. Each meter of cutting width can harvest 4 to 5 mu of wheat per hour.
- Vertical harvester
The cut crops stand upright on the cutter plane and are laid out in strips close to the conveyor. There are two types of vertical harvesters: side laying and rear laying
The side-laying harvester consists of a crop divider, a crop star wheel (or a crop finger wheel), a cutter, a horizontal vertical toothed belt conveyor, etc. The cut crops are pushed by the crop star wheel to the upper and lower toothed belts of the conveyor, and the conveyor transports them horizontally to one side of the machine for laying.
rear -laying harvester has a set of triangular belts with pulling teeth , star wheels and straw pressing spring strips added every 30 cm between the two straw dividers , so that the straw can remain in a stable upright state during the horizontal conveying process. After reaching the right side of the machine, it is transported backward by a pair of longitudinal conveyor belts, and the straw is laid into strips behind the machine with the help of the straw pressing plate . This type of machine can prevent the straw strips from being pressed on the corn seedlings when intercropping corn, and its cutting width is equal to the width of the wheat furrow between two rows of corn.
Vertical header harvesters are compact in structure, small in longitudinal dimension, light and flexible, and good in maneuverability, suitable for harvesting rice and wheat on small plots of land. They are usually matched with 7-9 kW hand-held tractors or wheeled tractors of about 15 kW, with a cutting width of 1.1-1.2 meters; there are also small self-propelled harvesters matched with 2-3 kW special hand-held chassis, with a cutting width of about 1 meter.
2. Key points for purchasing harvesters
- Selection of machine size
The power of a rice combine harvester is generally 9-107kW. Therefore, the size of the selected machine should be adapted to the size of the field and the conditions of concentrated and continuous fields . If the field is flat, large, and has a small height difference, a larger machine should be selected; if the field is small and scattered, a small harvester should be selected. If a large harvester is used for a small field, the efficiency of the harvester cannot be fully utilized; if a small harvester is used for a large field, the productivity is low and cannot meet the requirements of rapid harvesting during the busy farming season.
- Feeding method selection
According to the different feeding methods , rice combine harvesters are divided into semi-feeding and full-feeding models. The fundamental difference between the two is the different treatment of rice straw. The straw conveying device of the semi-feeding model is relatively complex, the price is high, and there are more failures. The full-feeding model has a simple structure, good reliability, fewer failures, and a relatively low price.
- Choice of walking device
For sandy and semi-sandy soils, which have a strong bearing capacity, a harvester with wheeled travel devices can be selected. For sticky and semi-sticky soils, it is better to choose a harvester with crawler travel devices. In addition, for backpack harvesters with wheeled travel devices, the harvesting tools can be unloaded during the slack season, and the tractor can be used for transportation; during the busy season, it can also be equipped with a plow, harrow or rotary tiller for farmland operations. However, harvesters with crawler travel devices are special harvesters with low utilization rates. Buyers should also consider carefully when purchasing.
- Harvest method selection
Rice combine harvesters can complete several processes such as harvesting, threshing and cleaning at one time. They are highly mechanized and the harvested grains are basically clean. They should generally be given priority. In some areas, due to economic conditions and the influence of traditional harvesting methods, people have long been accustomed to harvesting first, drying and then threshing. In this case, rice harvesters can be considered.
3. How to use the harvester
- Before harvesting, check whether all parts of the harvester are in good condition.
- Drive the machine into the field, then pull the grass dividing pole to the working position, lower the grain receiving platform, pull the grain discharge gate to the "open" position, hang the grain bag on the grain bag hook, and guide the machine to the vertical position of the ridge.
- Debug the machine, turn the dust control handle to the "standard" position, turn the auxiliary speed change handle to the " high speed " or "low speed" position according to the crop conditions , and put the grass discharge handle to the "cut grass" or "discharge grass" position.
- Lower the harvesting table so that the front end of the divider is 5-10 cm above the field surface.
- Move the clutch disengagement and clutch cut-off handles to the engaged position.
- Slowly push the main speed lever forward to start the machine harvesting.
- When the crops begin to enter the threshing port, operate the manual threshing depth adjustment switch to make the ear head be at the position away from the depth indicator mark.
- After all the crops have been harvested, the harvesting clutch handle is moved to the disengaged position.
- When the grain outlet stops discharging grain, move the clutch handle of the thresher to the disengagement position.
- Check whether all switches of the machine are closed. Reduce the throttle and turn off the engine.
- Drive the harvester back to the placement point and carry out certain inspections and maintenance.
4. How to maintain the harvester
4.1 Clearing away debris
- Thoroughly clean all components and connections of the machine, paying special attention to cleaning the remover and removing residues on the return plate.
- Clean the return tray of the cleaning machine.
- Clean any residue from the rollers and concave plates .
- Be sure to clean out the grain in the granary and elevators .
4.2 Full lubrication
plate oil or vaseline to each joint to prevent oxidation.
4.3 Separate storage
Some parts of the wheat combine harvester should be removed and kept separately.
