Intense vibration happens at the handle of the mini-tillers that abundantly used in mountainous and hilly areas of southwest China.It is absolutely essential to probe into the vibration characteristics and factors why handle of the tiller vibrates violently.Therefore,the vibration acceleration signals of a mini-tiller’s handle and engine cover were tested under the following four conditions:the engine being idle,racing at medium and high speeds,and the tiller working in the field with high engine speed.The signals were processed by means of the time domain eigenvalue analysis and the frequency spectrum analysis.The results showed that when the tiller was under static condition,with increase of the engine speed,the handle vibration decreased in the vertical direction,increased in the fore-and-aft direction and had marginal changes in the left-to-right direction.When the tiller worked at high engine speed,the handle vibrated most violently in the fore-and-aft direction,while the vibrations at the engine cover and handle decreased substantially in each direction,compared with the static conditions.Rotary blades cutting soil increased the damping of the whole machine so as to reduce the vibration at the handle and the engine cover,but the handle vibration was still violent.When the tiller worked,that soil absorbing energies of some frequencies led to the first order unbalanced inertia force of the engine becoming the main reason why handle vibrated intensely.
Since the subsidizing agricultural machine purchase was launched in 2004,the agriculture equipment industry in Chongqing has progressed by leaps and bounds,but it is still faced with a few urgent problems,which requires the coordination of stakeholders,with an aim to establish a clear direction of the development of industry and a technology route. With planting industry as an example,this paper applies the principle and method of industry technology roadmap to analyse the market demand,industry target,technology barrier and R & D demand of agricultural equipment industry in Chongqing. Based on the results,the top technology R & D items of agricultural equipment industry in Chongqing are obtained. Finally,the following suggestions are put forward: integrating resources,constructing platform and improving innovation ability; constructing agricultural industry park and promoting clustered development of agricultural equipment industry; strengthening finance and taxation support; strengthening construction of agricultural mechanization infrastructure; substantially developing socialized service of agricultural machinery.
