The increase of the tractor reliability can be reached only through the design of the tractor in function of the real loads applied in different components during the machine usage. In recent years the introduction of CAE software in the design and development phase has greatly contributed to this advancement in reliability, however the final validation of the machine is only completed after experimental tests. These tests - aimed at reproducing the vehicle load cycles and validate design model - require a large amount of time and represent a significant cost to the manufacturer. In any case the field test of the tractor in real world conditions is difficult due to the problems connected with the weather, the seasonality of the operations and the variability of the test conditions. As a consequence the tests performed on the field are not repeatable and fully reliable. In the past different procedures have been introduced to reproduce the loads acquired during field test on proving grounds or on 4 post-test rigs. Despite the use of both methods manufactures were only able to accurately reproduce vertical loads and accelerations, these methods were not able to reproduce the longitudinal loads frequently introduced on the tractors during field operations. It is possible to introduce longitudinal loads during proving ground tests by connecting a load cart to the tractor, but the commercially available load carts are not designed to generate impulsive loads transmitted to the tractor due to the implements interaction with the soil. Moreover commercial load carts are connected to the hitch instead of the three point hitch commonly used to connect an implement to the tractor. The aim of the paper is a feasibility study of the design of a load cart able to reproduce longitudinal impulsive loads transmitted by a three point hitch to the tractor to perform durability test on tractors. Measurements using different implements on different soil types were performed to define the loads transmitted by the implement to the tractor through the three point hitch. Then a dynamicmodel to simulate the connection between tractor-implement was defined to design the load cart. The load cart is constituted by a trailer connected to the three point hitch. The wheels of the trailer are braked in order to reproduce the draft acquired during field operations. The use of this load cart on proving ground will allow to reproduce the loads measured on the tractor during the whole life independently by the weather conditions.
Giovanni Molari, Michele Mattetti, Matthew Walker (2014). DRAFT SIMULATOR TO REPRODUCE FIELD WORK ON THE ROAD. The European Society of Agricultural Engineers (EurAgEng).
DRAFT SIMULATOR TO REPRODUCE FIELD WORK ON THE ROAD
MOLARI, GIOVANNI;MATTETTI, MICHELE;
2014
Abstract
The increase of the tractor reliability can be reached only through the design of the tractor in function of the real loads applied in different components during the machine usage. In recent years the introduction of CAE software in the design and development phase has greatly contributed to this advancement in reliability, however the final validation of the machine is only completed after experimental tests. These tests - aimed at reproducing the vehicle load cycles and validate design model - require a large amount of time and represent a significant cost to the manufacturer. In any case the field test of the tractor in real world conditions is difficult due to the problems connected with the weather, the seasonality of the operations and the variability of the test conditions. As a consequence the tests performed on the field are not repeatable and fully reliable. In the past different procedures have been introduced to reproduce the loads acquired during field test on proving grounds or on 4 post-test rigs. Despite the use of both methods manufactures were only able to accurately reproduce vertical loads and accelerations, these methods were not able to reproduce the longitudinal loads frequently introduced on the tractors during field operations. It is possible to introduce longitudinal loads during proving ground tests by connecting a load cart to the tractor, but the commercially available load carts are not designed to generate impulsive loads transmitted to the tractor due to the implements interaction with the soil. Moreover commercial load carts are connected to the hitch instead of the three point hitch commonly used to connect an implement to the tractor. The aim of the paper is a feasibility study of the design of a load cart able to reproduce longitudinal impulsive loads transmitted by a three point hitch to the tractor to perform durability test on tractors. Measurements using different implements on different soil types were performed to define the loads transmitted by the implement to the tractor through the three point hitch. Then a dynamicmodel to simulate the connection between tractor-implement was defined to design the load cart. The load cart is constituted by a trailer connected to the three point hitch. The wheels of the trailer are braked in order to reproduce the draft acquired during field operations. The use of this load cart on proving ground will allow to reproduce the loads measured on the tractor during the whole life independently by the weather conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
