Custom semi trucks with trailers 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.
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.
