Components of Crawler Undercarriage

Components of Crawler Undercarriage:

The crawler tracked undercarriage is the bearing base of the whole machine, which is composed of frame, track group, driving wheel, track roller, carrier roller, guide wheel and tensioning device, etc.

1-Track Group   2-Frame   3-Driving Wheel   4-Carrier Roller   5-Track Roller   6-Guide Wheel   7-Hydraulic Motor   8-Reducer

1. Track Group

Each steel track is composed of track shoes, track chain assemblies, etc. The track shoes are mounted on the left and right track segments with special steel bolts. The track section is the track on which the rollers roll. A pin sleeve is press-fitted into the front pin hole of each pair of track joints, and then it is hinged with the rear pin holes of the previous pair of track joints with a track pin. The track pin and the pin sleeve are in clearance fit. The rear pin holes of a pair of track segments are interference fit, so that the front and rear pairs of track segments are hinged with the pin sleeve through the track pins, and the front and rear track shoes can freely rotate relative to each other. After the track segments of the entire track are installed, a sleeve roller chain with guide rail surface is formed. The teeth of the drive wheel are engaged with the track through the pin sleeve. At present, the parts of the track assembly have been generalized, and the track shoes are all rolled track shoes with low quality, high strength, simple structure and low price. Great influence. The structure of track shoes is usually divided into track shoes for general use, wetland use, swamp use and rock ground use according to different uses.

The rubber track is a whole continuous crawler formed by rubber moulding. The core is reinforced with fabric and a plurality of steel wire ropes. The steel transmission parts are embedded in the vulcanized rubber belt. The main parameters of rubber crawler are pitch, number of sections, crawler width, pattern style, and embedded metal part style.

2. Frame

The undercarriage frame is the load-bearing structure of the tracked self-propelled chassis. The frame can be divided into combined type and integral type according to different structures.

The crawler frame of the combined frame is a frame structure. The beam is an I-beam or welded box beam, and the track frame usually adopts an open door-shaped section at the bottom, and the ends are fork-shaped for installation of driving wheels, guide wheels, and rollers. The advantage of this structure is that the frame structure can be changed according to the different size requirements of the length and width of the drilling rig, and the tracks of different lengths and widths can be installed by replacing the widened beam and the extended track frame. Its disadvantage is that the section of the crawler frame is weakened more, the rigidity is poor, and cracks are prone to occur at the weakened section.

The integral frame is welded with the beam and the crawler frame. It has the advantages of simple structure, compact arrangement, light weight and good rigidity. In addition, this structure can also make the diameter of the rollers smaller. According to the length of the tracked self-propelled chassis, the number of rollers can be installed 5 to 9 on each side. In this way, the weight of the machine can be evenly transmitted to the ground, which is more beneficial for ground use with lower carrying capacity.

3. Drive Wheel

The drive wheel is used to drive the track. It is mounted on the rear of the tracked self-propelled chassis. Its tooth pitch is generally half of the track pitch, that is, each tooth meshes with the track pin. In this way, after half of the teeth on the drive wheel are worn out, the other half can be replaced to work again to prolong its service life. But there are also tracks with a pitch equal to the pitch of the drive wheels. In this way, several joint pins can be engaged with the teeth at the same time, and the force is relatively uniform.

4. Carrier Roller

The carrier roller is used to support the upper track. Do not let it sag too much to reduce vibration during movement, and at the same time guides the direction of movement of the upper track to prevent it from sliding sideways.

The form of the carrier roller is similar to that of the roller, but it bears less force and has better working conditions, so its structure is relatively simple and its size is small.

The rear of the left and right support sliders is equipped with a tensioning device through the left and right fork arms. This slider-type tensioner has two ways to adjust the tension. One is the helical adjustment type, which consists of a tensioning screw and a tensioning spring. The other is the butter adjustment type, which consists of a hydraulic cylinder, a piston and a tensioning spring, which is the most widely used tensioning device. It injects butter into the tensioning device through the hand pump, and the position of the guide wheel is adjusted by the hydraulic cylinder and the plunger to achieve the track tension. The amount of butter injected into the hydraulic cylinder determines the tension of the track. If the track is too tight or the track needs to be removed, loosen the oil drain plug and squeeze out the butter to reduce the tension.

5. Track Roller

The roller is used to support the mass of the car body and transmit the weight to the track. During the driving process, it not only rolls along the track rail, but also clamps the track to prevent the track from sliding laterally and causing the track roller to derail. During mechanical steering, it forces the track to slide laterally on the ground.

Rollers often work in muddy water and dust, and are subject to large impact loads, resulting in poor working conditions. Therefore, it is required that its relative rotating part is sealed reliably, the rim is wear-resistant, and the rolling resistance is small. The unilateral rollers only have convex edges on the inside or outside of the two rims, while the double-sided rollers have convex edges on the inside and outside of the rims, so that they can better grip the track, but they roll Great resistance. Therefore, the number of double-sided rollers on each device should not exceed the number of single-sided rollers.

6. Guide wheel

The function of the guide wheel is to support the track and guide the track to be correctly wound. At the same time, it works with the tensioning device to keep the track to a certain degree of tension, alleviate the impact from the road, and reduce the vibration of the track during the movement. . Vibration during track motion can cause shock loads and additional power loss, accelerating wear between track pins and pin holes. When the track encounters an obstacle, the tensioning device can make the guide wheel move back a little to avoid excessive local tension of the track.

7,8. Travel motor and reducer

Choose domestic or imported motors according to your needs. The integrated two-speed or compact plunger hydraulic motor and reducer are usually recommended. The drive has the characteristics of small size, large traction, and low energy consumption; the travel motor and pipeline can be buried in the crawler to prevent the rough road caused by of damage. The travel motor is equipped with a parking brake and a balance valve to ensure smooth travel and stop and reliable braking.