What Is a Walking Brace?

The walking mechanism is also called "road mechanism", which is a part of the chassis of a car or tractor. It generally includes the frame, front axle, rear axle, suspension system, and wheels. The parts of the running mechanism that are in direct contact with the road surface are the wheels, which are called wheeled running mechanisms. In addition, there are several types of semi-crawler traveling mechanism, wheel-crawler traveling mechanism, and crawler traveling mechanism. The semi-tracked walking mechanism is equipped with wheels or skids on the front axle and tracks on the rear axle, which are mainly used in snow or swamps. The wheel-crawler travel mechanism has wheels and tracks that can be used interchangeably. The walking mechanism of a crawler tractor is composed of a suspension system and a crawler. ^[1]

The walking mechanism is an important execution part of the walking robot. It consists of a walking driving device,

The walking mechanism is divided into a wheel type, a track type, a walking type, and other methods according to its structure. The characteristics of each walking mechanism are discussed below.

Wheel type walking mechanism

Wheeled walking mechanisms have the advantages of smooth movement, low energy consumption, and easy control of the speed and direction of movement, so they have been widely used, but these advantages can only be exerted on flat ground. The currently used wheeled walking mechanisms are mainly three-wheeled or four-wheeled.

The three-wheeled walking mechanism has the most basic stability. The main problem is how to control the movement direction. The typical wheel configuration method is one front wheel and two rear wheels. The front wheel is used as the steering rudder to change the direction and the rear wheel is used to drive. The other is to drive the rear two wheels independently and the other wheel is only for support. , And rely on the speed difference or steering of the two wheels to change the direction of movement, so as to achieve the overall flexible, small-scale movement. However, when moving straight for a long distance, the diameter difference between the two driving wheels will affect the direction of advance.

The four-wheeled walking mechanism is also a widely used walking mechanism, and its basic principle is similar to the three-wheeled walking mechanism. The figure below shows a four-wheeled walking mechanism. Among them, the mechanism shown in Figures a and b uses two driving wheels and two self-retaining wheels (the latter two wheels in Figure a and the two left and right wheels in Figure b are the driving wheels); Figure c shows walking with a car The moving mechanism in the same way uses a four-link mechanism for steering, and the center of rotation is approximately on the extension of the rear wheel axle. The mechanism shown in Figure d can independently perform left and right steering, thereby improving the turning accuracy. All wheels of the indicator mechanism can steer, which can reduce the turning radius.

The traveling mechanism includes the traveling of the entire crane and the traveling of the lifting mechanism components. In addition to paying attention to its load GD ₂ and exercise resistance, it is also necessary to consider factors such as the slope of the walking route and the impact of wind and rain when walking outdoors to increase the friction torque. In addition to the friction torque determined by the motion resistance, the power of the walking mechanism must also consider the torque required during acceleration and deceleration. This torque is larger than the static torque, and its purpose is to reduce the acceleration and deceleration time and improve the operating efficiency. ^[3]

Generally, large-scale drilling rigs use crawler-type walking mechanisms, small-scale drilling rigs use tire-type walking mechanisms, and mining rigs mostly use crawler-type walking mechanisms. In order to make the drilling rig more flexible, each track should use a separate drive. In particular, small rotary drilling rigs are individually driven by oil motors abroad, and some rigs are driven solely by motors. The tire-type drilling rig is more suitable for mining scattered small ore bodies. The crawler-type drilling rig is mostly used in the stope with long operating time and relatively fixed working face. There are also some small rotary drilling rigs whose platforms can be fully swiveled in order to save the auxiliary operation time of moving the hole position. The walking speed of most rigs is between 1.2 to 2.8 km / h, the climbing ability is 10 ° to 15 °, and the specific pressure to ground is less than 1. For different open-pit mines, you can choose track shoes with different widths. ^[4]

According to the contact manner between the trolley and the track and the number of wheel rails, the walking mechanism is divided into four types: single-track single-wheel traveling mechanism, single-rail multi-wheel traveling mechanism, double-track two-wheel traveling mechanism, and multi-track multi-wheel traveling mechanism. The single-rail single-wheel traveling mechanism is called a trolley with one rail surface of a track; the other is called a single-rail multi-wheel traveling mechanism; and so on.

Single-track single-wheel walking mechanism

The monorail and single-wheel traveling mechanism (pictured) is a common traveling mechanism on cranes, and other forms of traveling mechanisms are derived from this mechanism. Because the horizontal force of the soft hook crane in the direction of the vertical track is small, a single-track single-wheel traveling mechanism is often used on the crane. Due to the large horizontal force in the vertical track direction of the opening and closing roof structure and the buoyancy of the roof upwards, there are very few moving roofs using single-track single-wheel walking mechanism. However, opening and closing roofs without small buoyancy can be considered for use.

Ordinary rail wheel connection scheme

Single-track multi-wheel walking mechanism

A single-wheel multi-track running mechanism is a wheel with different functions arranged on a plurality of tracks of a single track. The functions of these wheels are walking wheels, guide wheels and anti-floating wheels. In the wheel driving mode, the traveling wheels are driving wheels, and the wheels of other functions are driven wheels.

Walking mechanism of mobile roof of Maeno Elementary School Swimming Hall, Japan ^[5]

In the figure below, the walking mechanism can only move in the direction of the track, and the displacements in the four directions perpendicular to the track are restricted.

The picture below shows the moving mechanism of the mobile roof. It adopts a wheel-driven single-track multi-wheel running mechanism. The walking wheels are arranged in the tangential direction of the main truss of the mobile roof, and the track is also inclined in the tangent plane. Two vertical guide wheels are arranged in the vertical direction. The roof section is formed by the T-shaped cross section formed by the flange on the track and the web. The card floats on the wind. In order to ensure the safety at the prescribed different fixed docking positions, a hydraulically driven locking pin is provided on the running mechanism.

Mukogawa Gakuin Middle School Swimming Hall Mobile Roof Walking Mechanism ^[5]

The following figure is the opening and closing mechanism of the Ohita dome. This mechanism uses a steel cable drive method and a special-shaped monorail multi-wheel running mechanism scheme. The driving mechanism is installed on the floor, and the driving method is very simple. The profiled track has the function of profiled track, which restricts all directions except the direction of movement. This walking mechanism is different from the feature that the trolley is fixed on the mobile roof in general and moves with the roof. The trolley is fixed on the supporting structure of the mobile roof, and the roof moves on the trolley. In order to prevent the steel strand from conflicting with the structure, a guide wheel is specially arranged for the steel strand.

The single-track multi-wheel traveling mechanism is suitable for the case where the load in the plane of the traveling track is large, and the lateral load in the direction of the guide wheel perpendicular thereto is small. The traveling mechanism is compact and the size is small. Generally speaking, special-shaped tracks are more suitable for bearing larger lateral forces and anti-floating loads than ordinary monorail single-wheel tracks.

Ohita dome opening and closing mechanism ^[5]

Double-track double-wheel walking mechanism

Generally speaking, a dual-track double-wheel is a trolley arranged one wheel-rail device in two mutually perpendicular directions, the wheels in the main force direction are traveling wheels, and the other direction is the guide wheels. In the wheel driving mode, the traveling wheels are driving wheels, and the wheels of other functions are driven wheels. The double-track and two-wheeled walking mechanism is suitable for the case where the root of the moving roof or the walking mechanism only bears the unidirectional force and the horizontal combined force in one direction, and the size of the mobile roof is a small and medium-sized opening and closing roof structure. The following figure is a diagram of a small opening and closing roof structure walking mechanism. As a special case, the two wheels are arranged in the same direction, guided by the edge of the track, and resisted by L-shaped metal parts.

The following figure is the driving and walking mechanism of the Komatsu Dome. The mobile roof adopts steel cable traction and ordinary two-track two-wheel walking mechanism. Because the mobile roof adopts a herringbone hinge structure, the mobile roof generates vertical pressure and level on the support structure. Thrust, the mobile roof is also subject to windy buoyancy. To this end, the designer adopted a dual-track dual-wheel arrangement of a vertical wheel rail and a horizontal wheel rail to constrain and transmit vertical pressure and horizontal thrust. Due to the limitation of space size and building shape, the anti-floating of the roof does not adopt the ordinary wheel-rail scheme, but uses a special device. This device also has another function-to prevent the mobile roof from derailing in the event of an earthquake during the opening and closing process.

Komatsu dome driving and running mechanism ^[5]

It can be seen from the examples: from the perspective of the force, the trolley or the walking mechanism is subjected to the force in three directions, of which the load in two directions is large, and the other direction is the wind load with a small probability and a short duration. Constraints on joint forces or preventing derailment of the earthquake; from the perspective of constraints, the trolley needs to be restrained from three directions. The example uses a two-wheel dual-track running mechanism. The wheel and rail are arranged in two main directions of force. The anti-floating device for safety prevention in the direction of less force uses a non-axle device.

Multi-track multi-wheel walking mechanism

A multi-track multi-wheel running mechanism is that one or two ordinary wheel-rail running devices are arranged in each plane that needs to restrain the direction. These wheels are walking wheels, guide wheels and anti-floating wheels. Wheels arranged in the main force direction are called walking wheels. Wheels in the opposite direction to the walking wheels are anti-floating wheels. Wheels in the vertical walking wheel plane are guide wheels. Sometimes the guide wheel also has part of the function of a walking wheel. In the wheel driving mode, the traveling wheels are driving wheels, and the other wheels are driven wheels.

Multi-track multi-wheel walking mechanism is suitable for large-span, large-scale mobile roof systems. Because the wheel rails need to be arranged in the track grooves in four directions in the vertical walking direction, and the mechanical maintenance space is required, the stiffness, strength and dimensions of the track grooves and their supporting structures must be large.

In addition to the opening and closing roofs of the space moving method of partial block division, the multi-track and multi-wheel walking mechanism is suitable for the opening and closing structures of various rigid roof division methods. ^[5]