🔹 Log trucks’ elements 🔹

A special vehicle for transporting timber by means of a hauler consisting of a tractor and a hauler trailer, usually modified from a general purpose truck. Due to the thick and heavy wood, forest road slope, curve, poor road quality, climate change, the requirements of transport vehicles must have the following performance:

① high power;

② Equipped with special wood bearing equipment;

③ Ministries and institutions shall be of sufficient strength;

④ Can play a greater ability to pass on muddy or snow and ice road;

⑤ Simple structure, convenient operation and maintenance.

According to the transport form can be divided into log transport truck and the original transport truck. According to the form of loading and unloading of wood can be divided into self-loading truck and ordinary transport truck. According to the rated load capacity is divided into light, medium and heavy.

 

Structure

It is composed of engine, chassis and wood bearing device.

 

The engine

Generally, diesel engine and gasoline engine are divided according to the fuel used. Diesel engine is widely used because of its high thermal efficiency, low energy consumption and low diesel price. Logging trucks use 4, 6, 8 cylinder engines.

 

Automobile chassis

Including transmission system, walking system, steering system, braking system and auxiliary equipment. The transmission system is composed of clutch, transmission, transmission device and drive axle, etc., which ensures that the vehicle starts and stops, changes the driving direction and adjusts the speed. Walking by the frame, axles and suspension, shock absorber, wheel and tire, it the engine torque through the drive wheels and road surface adhesion effect, produce road to the driver of the vehicle (traction), transfer and support the weight of the vehicle and road of vehicle, the force and moment ease road of vehicle impact and ensure smooth traffic. The steering system is composed of steering gear and steering mechanism, which can ensure the straight running and change the driving direction of the vehicle. The braking system is composed of a brake and a brake transmission mechanism, which is used to slow down, stop and prevent sliding.

 

Wood bearing device

There are two basic types: one is the column plate,that is the general container; The other is the frame type, consist of turntable, bearing beam and car column and so on.

When the general truck is refitted to the special vehicle for transporting the logs, the container should be removed and the timber bearing device, turntable and guardrail should be installed. The bearing beam is fixed on the center line of the rotating plate. The installation of the bearing device must keep the original vehicle structure as far as possible, the center of gravity as low as possible, the steering is flexible, safe and firm, and the installation, disassembly, maintenance and maintenance are convenient.

The methods to determine the position of bearing beam are as follows:

(1) empirical method. The installation position of the bearing beam is determined by the automobile transport unit according to years of production practice experience.

(2) Geometric centroid method. The geometric center of the container before the modification of the truck is used as the installation position of the bearing beam.

(3) Axial load ratio statistical method. The load distribution ratio of front and rear axles of all kinds of vehicles under full load was calculated, and the lower limit of the load ratio of front axle was taken as the calculation basis for determining the installation position of bearing beam of specific models.

(4) Axial load distribution calculation method. The automobile is simplified as a simply supported beam, and the acting forces of various parts on the automobile before refitting and the bearing beam installed on the automobile after refitting are regarded as the concentrated force acting on the corresponding position of the simply supported beam. The torque of each force on the rear axle is taken, the balance equation is listed, and the distance between the bearing beam and the rear axle is solved. After modification, the load of each axle should still meet the rated load standard of the original vehicle.

 

Usability

Including load, speed, easy to use, passability, safety and economy.

(1) Load: ensure the maximum loading capacity under safe conditions. The load of rail-board (box) truck shall be stipulated by the manufacturer. In addition to the provisions of the manufacturer, the load of the log truck with the frame bearing device is also limited by the width of the bearing beam and the height of the vehicle column.

(2) Speed: the ability to complete the task of transporting materials at the highest driving speed. The factors that affect the average technical speed of the vehicle include the traction performance, braking performance and technical condition of the vehicle itself. There are road surface quality, curve radius, slope, slope length, etc.; Also with the distance and load, etc.

(3) Easy to use: the wood transporter can quickly and easily complete the performance of loading, transporting and unloading.

(4) Passability: the ability to pass through various roads, roadless zones or beyond obstacles at average technical speed.

(5) Safety: the ability to ensure that the logs transport truck does not rollover, crash and other accidents.

(6) Economy: the ability to complete unit transportation with the least fuel consumption.

 

Model selection

The log truck should have: adapt to the characteristics of forest stand composition, forest area road conditions and forest area climate. Durable, easy maintenance, spare parts supply is convenient, low fuel consumption.Automobile structure advanced, superior performance, easy to operate and so on.

The selection methods of the logging trucks are as follows:

(1) Empirical selection method. Through the use of various types of logging trucks, select suitable for the local log transporter model.

(2) Parameter selection method. By means of scientific analysis of the unit and external units of the use of the log trailer truck experience, put forward the parameters of the selected model, select the model that meets the requirements of approximate parameters.

(3) Efficiency selection method. With the computer can be compared in the use of various models can meet the constraints of the economic benefits can be achieved by calculation, from which the best economic benefits are selected.

 

🔹 How does the log trucks carry timber 🔹

Transport the timber produced by the logging area to the lumberyard and the unit that needs the timber by log trucks. It is widely used in the world because of its advantages of mobility and flexibility.

 

Transportation of materials by automobile

According to the type of timber, the vehicle transport is divided into log transport trucks, original log transport, felled transport, wood chip transport and branch transport. According to the type of vehicle, it is divided into single-vehicle transport and truck train transport.

 

Single-vehicle transport

The transport of timber by a single general purpose truck can transport both logs and other forest products and goods. In order to better meet the requirements of wood transportation in the forest area, the general truck can be refitted. In addition to retaining the original engine and chassis, the timber carrying device (including two bearing beams and four car columns) and cab protection device (guardrack) are added to the refitted truck. Some trucks are also installed on the chassis for loading and unloading of wood hydraulic crane arm. Because of the low efficiency and the underutilization of automobile power, it is widely used in high mountains, steep slopes, many curves, small curve radius and narrow roads.

 

The train transport material

The truck tractor and semi trailer are combined to transport the timber. According to the combination of truck and trailer, it is divided into two types: full hanging and half hanging.

(1) Full hanging type material transport car train: it is composed of load bearing traction car and full trailer. The trailer is connected with the tractor by means of a pole, and the front axle is provided with a turntable. Used for loading logs, short car columns are installed on both sides of the trailer bottom plate, and the front end of the car bottom plate is provided with guardrail or box plate to prevent the log from impacting the cab forward when the vehicle is braking.

(2) Semi-hanging type transport vehicle train: it is composed of a saddle tractor and semi-trailer equipped with a supporting coupling device. As the distance between the axle of semi-trailer and the rear axle of tractor can be greatly extended, the floor area and loading volume of the truck are increased. The configuration of the car column should not only consider the long log, but also facilitate the transportation of short logs, its interval should be appropriate. Compared with the bicycle, the speed of the car train is lower, the mobility is poor, the turning radius is large, the reversing is difficult and the dead weight is larger, but the freight efficiency of the truck train is higher than that of the bicycle. If the bottom plate of the semi trailer is very long, it can also be used to transport the original strip. The big end of the original bale for train transportation is placed on the bearing beam of the truck, and the small end is placed on the bearing beam of the trailer. The original size of the bale can also be inverted on the truck train.

 

Trucking efficiency

Under the condition of certain transport distance, the main factors that affect the transport efficiency of vehicles are load, vehicle speed and residence time. The larger the load, the faster the speed and the shorter the residence time of the vehicle, the higher the efficiency of the vehicle transporting materials. In addition, the organization and management of the vehicle transport also has a great impact on the vehicle transport. In order to improve the efficiency of transporting materials, the following measures should be taken:

(1) Try to use the truck train transportation, and combined with the forestry enterprise specific road, forest resources and other conditions, determine and maintain the reasonable load of the truck train.

(2) Choose good power, braking and mobility of the truck, and keep the vehicle and the road in good condition. Under the condition of ensuring safe driving, use direct gear and high gear as far as possible to improve the running speed of the vehicle.

(3) Try to compress the stay time in the loading yard and the lumberyard. For this reason, the method of large bale loading and pre-loading can be adopted in the lumbering area, and the storage and sheltering area can be set up in the lumbering yard.

 

🔹 Expectation 🔹

In the future, we should adopt new equipment and technology to improve the management level of log trucking. Its main measures are:

(1) Do a good job in the selection and finalize the work of the logging trucks and its process equipment.

(2) Develop new trailer and reasonably match with the log trucks.

(3) The haulage road is extended into the cutting area as far as possible in order to shorten the collecting distance.

(4) Experiment and research on felled timber transport.

(5) To establish an effective and reliable dispatch center, the combination of electronic computers and wireless communication, timely grasp the loading, transportation, unloading, reasonable command of the vehicle transportation.

(6) Gradually adopt shuttle transportation method (a tractor is equipped with 2 ~ 3 trailers), so that the tractor or truck train make full use of the working time.

(7) Using modern management methods to analyze the benefits of automobile transport.