M.Yu.Smirnov, Yu.S.Andrianov ( the Mari State Technical University, Yoshkar-Ola, Russia )

The perspectives of roundwood assortiment hauling in the Mari El Republic

Lately in Russia and also in the Mari El Republic wood- and forestry enterprises increase the felling volume of timber as per the assortiment’s technology. The hauling rigs with hang hydro-manipulators ( with hang hydro-knuckle booms ) are widely used for the roundwood assortiment loading and assortiment hauling. In this case the most wide spread scheme of the hauling rig is “hauling truck + pole trailer”.The analysis of the work of these hauling rigs in different enterprises of the Mari El Republic revealed the following main drawbacks: the excessive overload of the hauling truck’s bunk; the considerable overloading of the pole trailer’s bunk; the small load capacity of the hauling rig; the uneffective use of the hauling truck’s thrust force; the lowering of the useful load in comparison with the tree length hauling.

On the basis of the all-round analysis of the possible schemes of the staffing of the hauling rigs of the short log trucks it was established that the most perspective scheme is “hauling truck + trailer”. The main advantages of this scheme are: the large load capacity; the possibility of the guaranteeing of the considerable useful loads; the complete use of the hauling tractor’s thrust force; the guaranteeing of the middle value of the tare’s coefficient of the hauling rig; the possibility of the simple regulation of the total mass of the hauling rig and load by means of change of the trailers of different lifting capacity by changing of the road’s conditions.

The relief’s study in the Mari El Republic, the conditions of the roads’ building and the roads’ state allowed to make the following conclusion: the full – driving hauling truck “KAMAZ - 43105” ( КамАЗ – 43105 ) should be used for the assortiment hauling directly from the cutting areas along the dirt roads. In this case it would be desirable to use the long – based full – driving hauling truck. The hauling truck “MAZ - 83781” ( МАЗ - 83781 ), lifting capacity 142 kN, should be used as the main trailer to the long – based full – driving hauling truck. The recommended hauling rig is up to the requirements of the Traffic Rules in full measure and it can drive on the roads of the general system without obstructions. It allows to haul timber not only to the enterprise’s storage but into the consumer’s yard.

The hydraulic manipulator ( the hydraulic knuckle boom ) should be mounted on the hauling rig to provide the self-loading of the hauling rig with roundwood assortiment. In this case the home manipulators ( knuckle booms ) “SF – 65S” ( СФ-65С ), “LV - 185” ( ЛВ-185 ), “PL - 70” ( ПЛ-70 ) and others can be used. The loading mechanism on the hauling rig can be fixed in the back part of the truck or in the front part of the trailer. These variants are not equivalent because they ensure different loads. The mounting of the manipulator ( knuckle boom ) on the transport unit demands to bring down its lifting capacity for preservation of values of the axial loads. The allocation of the loading mechanism on the trailer in the trailer's front part is very advantageously. The possible useful load in this case is increased by 1,9 CBM or by 8,7% in comparison with the allocation of the manipulator ( knuckle boom ) in the back part of the truck.

The economic effectiveness of timber hauling by the self-loading hauling rigs is defined. The hauling rig “KAMAZ – 43105 + MAZ - 87781” ( КамАЗ – 43105 + МАЗ – 87781 ) but without hang manipulator is taken into account as the based variant. Its load is 26,5 CBM and it exceeds the analogous index of the self-loading hauling rig by 2,7...4,6 CBM depending on the allocation of the manipulator ( knuckle boom ). The self-propelled timber loader “PL – 1V” ( ПЛ – 1В ) and tower crane “KB - 572” ( КБ – 572 ) are taken into account in the based variant as the loading- and unloading mechanisms. Timber – loading expense is taken into consideration in the economic calculations completely. The crane’s expense is taken into consideration proportionally to time of its work regarding the unloading operations.

The economic researches of the work of the self-loading hauling rigs showed the following positive aspects of its use. Namely: the raising productivity of labour by 1,3 – 2,7 times; the lowering of the volume of investments, the lowering of the working- and combined costs by the distances of timber hauling up to 70-90 km depending on the hauling rig and its load; the reduction of necessity in machines and mechanisms, in workers and in the required fund of remuneration of labour. The negative aspects are: the increase of the capital-, working- and combined costs by the great distances of timber hauling; the increase of necessity in fuel lubricating groove materials; the increase of the tare’s coefficient of the hauling rigs.

The calculation annual economic effect of the use of the projected self-loading hauling rigs in conditions of the Mari El Republic is 515...115 000 rb depending on the distance of timber hauling calculating on 10 000 CBM.

Taking into account the structure of the logging in the Mari El Republic and the formed distances of timber hauling, the use of the self-loading hauling rigs for the loading and timber hauling should be considered perspective and proved to be correct from the economic point of view. It is recommended to make timber hauling into the consumer’s yard by the distances exceeding 70...90 km by the hauling rigs without hang loading mechanisms.