A hydraulic manifold, sometimes called a hydraulic valve block, is a machine component which regulates the fluid flow between the actuators, pumps and other components within a hydraulic system. In terms of functionality, it is similar to a switchboard of an electric circuit as it allows the operator to control the movements of fluid between different parts of a hydraulic machinery. For instance, in a machine such as a backhoe loader, the manifold turns on, turns off and diverts the flow of the fluid towards the telescopic arms of the both the front and backbuckets. In this case, the hydraulic manifold is attached to the levers present in the operator’s cabin of the machine, and the operator uses it to get the desired movements.
A manifold is created by attaching several assorted hydraulic values to one another. The different combinations of the states of these values is responsible for the sophisticated control behaviour of a manifold. The flow of the pressurized oil is controlled by valves located inside the manifold and is then passed via the hoses to a work device, like a hydraulic motor.
Apart from providing a neat logical layout, the consolidation of components inside a hydraulic valve block reduces the number of fittings, assembly time and avoids sudden pressure drops and leak points. Some engineers consider manifolds as black boxes that may not be of much help while troubleshooting. However, if the system is well-designed by placing the test points in key places, identifying the problem which causes a malfunction is not that difficult. By connecting a transducer to a test point, the data can be linked to the machine’s PLC and may be displayed on the Human Machine Interface (HMI). Major applications that use manifolds include heavy construction machinery, machine tools, value operations, material handling and production equipment, marine machinery, food processing, and off-highway machinery.
Types Of Hydraulic Manifolds:
There are two basic types of hydraulic manifolds or hydraulic valve blocks. The first type comes in a mono-block design which holds the values and passages of the entire system. The second type is a modular block design that supports only 1 or 2 valves and has special interconnecting passages for the values. In real world scenarios, a modular block unit will be connected to a series of similar units to create a much bigger system.
A) Mono-Block Design:
The mono-block manifolds are further subdivided into laminar and drilled metal blocks.
Laminar manifolds are generally made from steel with passages created by milling through multiple metal layers. These metal plates are stacked one above the other with fluid paths between them. Finally, solid-metal pieces are added, and the entire stack is brazed into a single unit. Now, these manifolds are capable of tolerating high pressures of up to 10,000 psi. The internal passages may be created in any required shape, so almost any flow-rate can be maintained with negligible drop in pressure. In a laminar manifold, all connections including the values can be placed anywhere you need, depending on your application. However, due to their brazed construction and their permanently-shaped flow passages, this type of manifolds are not easily modifiable if any circuit changes are required in future.
Drilled metal blocks are created from bars or plates made of aluminium, ductile iron and steel. It is quite obvious from their name that they are formed by drilling metal blocks in order to create flow passages and circuit paths. You may place the valves anywhere you please, however the drilled passages should always be straight. Other types of drilled-block manifolds accommodate cartridge valves into the cavities drilled deep into the surface of the manifold. In such a case, several interconnecting flow-passages start from the valve cavities and run into the manifold. Some cartridge valves comprise of threaded bodies which hold them in place within threaded cavities while others slip inside smooth cavities in which they’re held by plates.
B) Modular Block Design:
The modular manifold systems can easily be modified or attached to other existing manifolds. They’re typically made of steel, aluminum and ductile iron and are available in both standard and custom designs. The ends of these manifold blocks are sealed with “end pates” which can be drilled further for tank or pump connections. In addition, the spacer, interconnecting and divider plates are installed within the basic building blocks. Spacer plates can increase the dimensions of the basic blocks so that an over-sized valve can be inserted. The interconnecting plates divert the flow of the fluid from one passage to another between the blocks. They also serve in stopping the flow between two blocks by stopping a passage. The divider plates facilitate or block the flow by plugging.
The top portion of a basic modular manifold block is drilled and ported to accommodate subplate-mounted valves. Also, blocks with multiple ports are available for every type of sub-plate and valve. Each type is uniquely identified by the valve it can accept. Few mounted systems accept both cartridge valves and sub-plate mounted valves. Whenever you specify a manifold system, the interchangeability of blocks, subplates and valves should be considered carefully.
The electrical connections to manifolds are created using wires that run directly from the power source to the respective solenoid. Many manifold systems have inbuilt electrical channels or troughs for interior arrangement of electric cables. Since there is a diverse range of configurations available for manifold design, multiple software packages have been created to help the engineers in designing a manifold system. With advancements in the design software and the CNC technology, the manufacturing cost of custom mono-block or modular manifolds, even in less number, is quite reasonable.
Things To Keep In Ming When Choosing A Manifold:
1. What fluid is used?
2. Seal materials
3. Duty cycle
4. Electrical connections and voltage
5. Maximum and working pressure
6. Material and finish
7. Operating temperature and environmental factors
8. Flow conditions such as pump, return and accumulator
9, The location, size and type of the ports
10. Type of/Number of valves
Benefits Of Hydraulic Manifolds:
These components, which play an important role in any fluid power system, are used in a wide array of applications. With the global energy crisis and the rising demand for efficiency, manifolds are increasingly becoming crucial to OEMs, fluid power engineers and ultimately, to the end users.