Modularity for Mobile Hydraulics

The demands placed on a modern hydraulic system in mobile working machines are varied:

• Reliability
• Energy efficiency
• Ease of maintenance
• Compact design

Control blocks from ARGO-HYTOS provide the flexibility necessary for efficient solutions. Different designs, sizes and control strategies can be combined to reach an application-specific Optimum.

The control block is divided into three sections:

1. Standard catalog products for flow rates up to 25 l/min.
2. Application-specific control block with screw-in and flangeable valves (UNF¾ ,7/8 and ISO-4401)
3. Sandwich sections from modular systems, nominal size 6 (LS-connection, directional control valves (DCVs), proportional control valves (PCVs), with and without pressure compensators)

In general, there are two types of consumers in mobile machines: consumers that are actuated and operated frequently or permanently during operation, and consumers that are used rarely or sporadically, e.g. actuating movements.

Only in rare cases are the permanently operated consumers supplied with maximum pressure at all times, so a LS circuit in conjunction with a control pump for these functions is often the chosen solution. By using control pumps, the energy consumption can be brought much closer to the “real” demand of the function. The precondition for this is created by section 3 of the control block, which taps the LS signal, limits it upwards and also relieves it, if necessary. A main pressure protection can also be realized and integrated in the inlet section.

In section 1, a simple throttle control is realized by means of DCVs. The actuating and auxiliary functions supplied here are used sporadically, here, an LS circuit is not mandatory. Savings in terms of cost, weight and space are paramount. 4/4 and 4/2 directional control valve functions have been configured in addition to the usual locking and pressure functions from our catalog. Quick and subsequent adjustments are also possible during the course of testing, by changing the tie rods and sandwich valves, both number of consumers and functionality can be easily adapted.

Switching from the LS system to the constant pressure system takes place in the central inlet section by means of a ¾ UNF screw-in valve. By operating the 3/2-way valve, the control pump is supplied with control pressure and opens; it supplies the control block with the preset maximum pressure. The pressures of the LS sections and the constant pressure sections can be adjusted independently of each other. An electrically proportional adjustment is easily feasible by replacing the valves. Parallel operation of the two sides is just as feasible as a priority circuit for one of the two functional units, which is implemented in the central inlet section.

In most cases, the central inlet section is a customer-specific aluminum control block, which is designed according to the conditions in the system. In addition to the mounting options, the size, position and arrangement of the connections are the determining factors in the design of the inlet section. In the arrangement we are free and can fully consider the customer needs.

We rely on tried and tested principles and schematics regarding design and functionality. For years, these design concepts have been used successfully in a wide variety of agricultural and construction machinery. The further development and adaptation of the switching logic behind the LS switching and “conditioning“ of the LS signal is operated in all directions: manually operated, electrically, electro-sensorially or hydraulically automatic.

The functional principles and design options presented here are suitable for a wide variety of agricultural and construction machines – sprayers, balers, combine harvesters, forage harvesters, reach stackers, potato and beet harvesters, planting and seed drills, to name only a few.

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