(1) hand-propelled hob mower
This lawn mower is a small manual mowing tool with the characteristics of no vibration, no noise and no pollution. This model is mainly composed of driving wheel, gear transmission mechanism, hob, bottom cutter, height adjustment mechanism and operating handle, as shown in Figure 4- 19. When in use, the operator pushes the lawn mower to move on the lawn, the hob rotates with the driving wheel rolling on the ground, and the hob cooperates with the bottom knife to finish the grass cutting operation.
Figure 4- 19 Hand-pushed unpowered hob mower
The height of grass can be adjusted as needed, generally 6 ~ 25mm. Hand-propelled unpowered lawn mower is suitable for lawns with grass height below1.20mm. When the grass height is above 120mm, the tall grass must be cut before using this machine. Before mowing the grass, remove the stones, branches and other hard sundries on the lawn to avoid damaging the edge of the hob.
Hand-propelled hob mower has high labor intensity and low working efficiency, and its ground wheels are repeatedly crushed on the lawn, which causes great damage to the lawn and low trimming quality. Only suitable for small lawn mowing with low requirements.
(2) Walking self-propelled hob mower
This is a hob mower widely used at present. It consists of engine, transmission system, walking device, hob cutting device and control mechanism, as shown in Figure 4-20.
Figure 4-20 Structure of Walking Self-propelled Hob Mower
The walking self-propelled hob mower has two characteristics in structure. First, because the hob rotates around the horizontal axis, its engines are all vertically arranged, which is convenient for transmission. The hob rotates around the vertical axis, so its engine is mainly arranged horizontally. Secondly, because the hob shaft and the driving wheel shaft are both horizontal shafts, there is no need to change the transmission direction in the transmission system, and the structure is simpler than that of the rotary cutter. Figure 4-2 1 shows a common transmission structure. The power of the engine is transmitted to the reducer through the friction clutch, and then to the hob shaft through the transmission belt. One way is to drive the hob to rotate through the clutch, and the other way is to transmit the power to the active walking wheel through the two-stage chain transmission, so that the machine can walk on its own. This transmission mode is to ensure that the circumferential linear speed of hob blade matches the advancing linear speed. The engagement and disengagement of hob rotation is controlled by another clutch. Some hob cutting devices are also equipped with brake clutches. When the clutch is powered off, the hob can be braked immediately to ensure safe operation.
Fig. 4-2 1 transmission box of walking self-propelled hob mower
(3) Install the hob mower
The appearance of the hanging hob mower is the same as that of the hanging rotary mower, and the engine is placed behind the driver's seat.
The front or back, as shown in Figure 4-22, is a shape with a hob mower. The machine is driven by hydraulic pressure and driven by four wheels. Three groups of hob cutting devices are arranged in front, and two groups are arranged between shafts. Each group of cutting devices is driven by a hydraulic motor. Its basic feature is good safety, which ensures the driver to avoid the danger and injury of rollover. When trimming slopes and embankments, it can be remotely controlled by radio to ensure safety. When mowing the golf course lawn, each cutting device can be equipped with a grass collection box to collect the cut grass.
Figure 4-22 Shape of hanging hob mower
(4) Tractor traction hob mower
Tractor traction hob mower is to hang the hob cutting device on the ordinary tractor (the lawn must be replaced with pneumatic tires), and the cutting device is placed behind the tractor and towed by the guide frame, as shown in Figure 4-23. The power sources of each group of traction cutting devices mainly include: first, the ground wheels at both ends of the cutting device drive the hob shaft, and the ground wheels are dragged and rolled by tractors, usually pneumatic lawn tires; Second, the power output shaft is driven by the gearbox respectively; Thirdly, the hydraulic pump is driven by the power output shaft and then by the hydraulic motors installed on each group, or the full hydraulic transmission is driven by the hydraulic motors respectively. Traction hob mower generally has more traction cutting devices and higher productivity, and is suitable for mowing large lawns. Each group of cutting devices is equipped with a clutch in the ground wheel drive, so that the cutting devices can be disconnected from the power supply in the transportation state, and the hob will not rotate and cause accidents. During transportation, the cutting devices on both sides can also be hung to reduce the lateral width and protect the cutting devices.
Figure 4-23 Tractor Traction Hob Mower
(5) Tractor hanging hob mower
Tractor-suspended hob mower generally hangs 5 or 7 groups of cutting devices, each group is driven by hydraulic motor, as shown in Figure 4-24.
Figure 4-24 Tractor Hanging Hob Mower
. Its power comes from the hydraulic pump driven by the tractor power output shaft. The pipeline of the hydraulic system delivers high-pressure oil to the hydraulic motor installed at the end of each cutting device, and the hydraulic motor drives the hob shaft to rotate for trimming operation. Because the rotating speed of the hydraulic motor can be adjusted, the driver can adjust its matching with the driving speed of the tractor according to the specific situation and pruning quality of the lawn grass.
Hydraulic system can also be used to realize the lifting of hob cutting device. When the hydraulic cylinder lifts the cutting device off the ground, tilts, stands upright or folds, it is more convenient to transport or transfer the work site. Therefore, the hanging hob mower is superior to the traction mower in terms of operation flexibility and transportation maneuverability, and it is the main type of hanging hob mower (Figure 4-24).