Mechanical Technology January 2015

⎪ Hydraulic and pneumatic systems ⎪

This article reports on the customisation by Bosch Rexroth of its Eurocentric EHC-8 electro-hydraulic hitch control solution to suit the Indian agricultural market with its rugged and more variable ground conditions. Optimised hitch control for Indian ploughs

productivity and operator safety. Another modification required to enhance the hitch’s viability in these conditions was resistance to leaks. The IP 67 protection code adhered to in European environments was not suited to the dusty conditions experienced in Asia, requiring a modified sensor and the separation of electrical components from the mechanical space. The controller software also had to be adapted, shifting from the European lower linkage to upper linkage control. Because this configuration only requires one power regulation sensor instead of two, Bosch Rexroth was also able to reduce production costs. The company reduced costs in several other areas as well. Because the plastics used in the construction are sourced locally, sourcing them is cheaper, in addition to being more tol- erant of the local conditions, offering a slightly more durable service life. Local manufacturers are also producing the EHR5 hydraulic valve, which regulates the flow of hydraulic fluid to the cylin- ders for greater precision of movement control for the lifting unit. Further research and development is planned for the hitch control beyond the commencement of mass production in the first quarter of 2015, including the implementation of a power measure- ment sensor tailored to local power ranges. q

The saturated, muddy sludge that can characterise Asia’s arable land presents unique performance challenges for electrical and mechanical components.

B osch Rexroth, distributed in southern Africa by the Hytec Group of Companies, has optimised its EHC-8 electro-hydraulic hitch control in order to replicate the same precise regulation of power and positioning for the lifting and lowering of towed agricultural ploughs in Asia as has been delivered to European and North American markets. In the transatlantic environments for which it was principally designed, the EHC-8 enhances agricultural ap- plications through a greater control of implement depth, which increases the accuracy of tillage, turning soils gently and uniformly for improved yields. The same levels of project satisfaction were not, however, originally replicated out- side of these regions due to the vastly different climactic and terrain condi- tions and yields, necessitating Bosch Rexroth to modify and re-engineer certain core components and mechani- cal designs that comprised the EHC-8 control to meet the specific needs of Asia’s agricultural markets. The first step of tailoring such a solution, was a detailed analysis of the operating conditions. Many regions are affected by monsoon climates, high rainfall and high humidity conditions in which excessively saturated land poses unique challenges to the use of mechanically-propelled implements. The winter months endured by these regions, conversely, present hot, dry and

dusty conditions, extending the loading demands on equipment components.

Designed for extremes In optimising the hitch control for operation in these conditions, two com- ponents in particular required modifica- tions: the angular sensor and the control panel. The control panel was optimised for enhanced rough terrain capability through the application of a protective film, while increased brightness offered greater visibility under intense sunlight. The control panel was installed into the operator armrest to provide maximum ergonomic operability for improved

The modified components used in the EHC-8 electro-hydraulic hitch control, including the angular sensor and redesigned control panel.

Mechanical Technology — January 2015

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