The tread and material design of special tires for wheel excavators mainly focuses on the four core requirements of "load-bearing capacity, grip performance, wear and damage resistance, and adaptability to multiple working conditions". These tires need to balance the stability of road driving and adaptability to complex ground in construction sites, while withstanding harsh scenarios such as heavy loads, sharp obstacles, and muddy conditions. Their design considerations are strongly related to high adaptability to ground conditions, which are detailed as follows:
The core functions of wheel excavator tire treads are water and mud drainage, enhancing adhesion, dispersing pressure, and resisting cuts and wear. Different tread structures correspond to different operating scenarios, with highly targeted design details:
Design Considerations: The tread is distributed in independent blocks. The blocks are wide and thick, with a deep tread depth (usually 15-25mm), and there are wide and connected grooves between the blocks. This design can increase the contact area between the tire and the ground, improving stability under heavy loads. The wide grooves can quickly drain mud and gravel, preventing the tread from being blocked and causing slipping. Some high-end tires add chamfer designs at the edges of the blocks to reduce cut damage to the tread from sharp objects.
Applicable Scenarios: Comprehensive working conditions such as urban and rural road construction, general earthwork operations, and sand and gravel sites. It balances road transfer and light complex ground operations.
Design Considerations: The tread is mainly composed of transverse grooves. The grooves are wide and deep, running transversely across the entire tread surface. Some treads are equipped with raised "anti-slip teeth". The transverse structure can enhance the tire's "bite force" on soft ground. The wide grooves can efficiently drain mud and accumulated water, preventing the tire from sinking into mud and losing grip. The anti-slip teeth further improve traction on muddy ground.
Applicable Scenarios: Low-adhesion ground such as farmland water conservancy construction, muddy sites after rain, and marsh edges.
Design Considerations: It combines the advantages of block treads and transverse treads. The middle part of the tread adopts longitudinal treads to ensure guidance and water drainage during road driving. The shoulder and both sides use large block treads to enhance off-road grip. The tread blocks adopt an asymmetric design; the outer blocks are larger and thicker to withstand lateral forces during site operations, while the inner tread grooves are denser to improve stability during road driving.
Applicable Scenarios: Working conditions that require frequent switching between roads and complex sites, such as urban demolition, municipal emergency repairs, and mountain road construction.
Design Considerations: The tread has no obvious raised patterns or extremely shallow patterns. The tread surface is flat and thick, with high rubber hardness. This design can maximize the tire's ground contact area, disperse pressure, prevent sharp gravel from embedding in the tread and causing tire damage, and enhance adhesion on hard ground.
Applicable Scenarios: Working conditions with hard ground and many sharp gravels, such as mining operations, cement ground operations, and construction waste removal.
Wheel excavator tires need to bear the machine's own weight (usually several tons to dozens of tons), impact loads during operations, and friction from complex ground. The material formula and structural layer design directly determine their service life and safety. The core considerations are as follows:
Wear and Cut-Resistant Formula: The mainstream formula is a composite of natural rubber, synthetic rubber, and reinforcing agents. Natural rubber accounts for 40%-60% to ensure the tire's elasticity and toughness. Synthetic rubber (such as styrene-butadiene rubber and cis-polybutadiene rubber) improves wear resistance. Reinforcing agents such as carbon black and silica are added to enhance tread hardness and tear resistance. For extreme working conditions like mining, wear-resistant resins and cut-resistant fibers are added, making the tread hardness reach 65-75 Shore A.
Aging, High and Low Temperature Resistant Formula: Anti-aging agents and antioxidants are added to prevent the tire from cracking and hardening under outdoor exposure and low-temperature environments. Some tires use low-temperature elastic rubber to adapt to operations in cold areas and prevent rubber from becoming brittle due to low temperatures.
Skeleton Material: The carcass cord layer uses high-strength polyester cords or steel cords. Polyester cords are lightweight and have good elasticity, suitable for small and medium-sized wheel excavators. Steel cords have high strength and strong load-bearing capacity, suitable for large wheel excavators and heavy-load working conditions. The number of cord layers is usually 8-16; more layers mean stronger load-bearing capacity of the tire.
Buffer Layer and Belt Layer: A buffer layer is installed under the tread, made of high-elastic rubber to absorb impact loads during operations and protect the carcass. The belt layer uses spirally wound steel belts to enhance tread rigidity, prevent tread deformation, and improve stability during high-speed driving.
Thickened Sidewall Design: The rubber thickness of the sidewall is 2-3 times that of ordinary car tires. Some models also add wear-resistant rubber strips or Kevlar fiber layers to the sidewalls to prevent scratches and punctures by sharp objects such as gravel and steel bars during operations.
Anti-Fatigue Formula: Elastic additives are added to the sidewall rubber to improve flex resistance, preventing sidewall bulging and cracking during frequent steering and bumpy.
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