In the work truck industry, hydraulic systems are a staple, used almost daily for various tasks. To carry out hydraulic work, two key conditions must be met: flow and pressure. While both are essential, either can be controlled to regulate the hydraulic work.
These terms describe the construction of the directional control valve and the type of hydraulic circuit in use. In an open center system, flow is continuous while pressure is intermittent, contrasting with a closed center system where the flow is intermittent, and pressure is continuous.
Open Center Systems
In an Automotive Lift Repair Florida open center system, as the pump operates, flow is generated and directed back to the tank via a central passage in the directional control valve. When a spool in the valve is activated, the flow is directed toward a load, creating pressure. Once this pressure exceeds the load, the load moves, and the hydraulic work is performed.
Closed Center Systems
In a Automotive Lift Repair Florida closed center system, the pump also generates flow, but only enough to maintain lubrication and achieve standby pressure at the directional control valve. When a spool is activated, it opens a passage for flow and sends a pressure signal from the valve to the pump, instructing it to produce the necessary flow for the hydraulic work.
Open vs. Closed
In simpler terms, an open center system allows oil to flow continuously through the open center directional control valve, regardless of whether work sections are in use. In contrast, a closed center system’s valve communicates with the pump, so when a work section is not in use, the pump reduces its output, minimizing oil displacement.
Typically, open center systems are less expensive due to the use of a fixed displacement pump, which costs less than the variable displacement pump often found in closed center systems. Although more expensive, closed center systems are generally more efficient as they do not continuously circulate oil through the valve when it is not needed, leading to energy and fuel savings.
Converting Automotive Lift Repair Florida Systems
It’s possible to convert open center systems to closed center systems and vice versa, although systems are usually designed as one or the other from the start. Converting an open center system to a closed center system often requires additional components, such as a full-flow dump valve, to allow the pump to release excess flow when not needed.
A fixed displacement pump can be used in a closed center system, but proper setup is crucial to ensure the system functions correctly. Conversely, converting a closed center system to an open center system involves adjusting the outlet and opening internal passages in the valve to allow free flow of oil to the tank. However, not all valves are designed to allow such a conversion.
When selecting a hydraulic system design, it’s essential to consider the specific application or system requirements. Understanding the differences between open and closed center systems, the hydraulic work needed, and the balance between cost and efficiency is critical in making the right choice.
Open and Closed Circuit Hydraulic Pump Systems: An Overview
If you’re familiar with Automotive Lift Repair Florida hydraulic systems, you’ve likely encountered the two common types of hydraulic circuits: open loop and closed loop. Each has its own set of advantages and disadvantages, making it crucial to understand the differences to choose the best circuit design for your hydraulic system.
What Is an Open Loop Hydraulic Circuit?
An open loop circuit connects the inlet of the hydraulic pump and the return flow from the hydraulic motor or actuator to the hydraulic fluid reservoir. The pump provides a continuous flow of fluid through the system. This circuit type often utilizes directional control valves to regulate flow and system pressure to actuators.
Advantages of an Open Loop Circuit
– Runs cooler since heat dissipates in the reservoir
– Supports multiple control valves in a series
– Offers greater flexibility in system design
– Lower risk of fluid contamination
– Suitable for circuits with actuators other than motors
– Less expensive to configure and design
– Easier to maintain
Disadvantages of an Open Loop Circuit
– Requires a large fluid reservoir for proper cooling
– Can generate excessive heat if the reservoir is too small
– Complex systems can be more difficult to troubleshoot
What Is a Closed Loop Hydraulic Circuit?
A Automotive Lift Repair Florida closed loop circuit, also known as a hydrostatic drive, circulates fluid in a closed system. Fluid flows from a piston pump to a motor and back to the pump without passing through a reservoir. Typically, a pressure control relief valve allows hot fluid to escape when necessary, and a gear pump acts as a charge pump to draw cooler fluid from the reservoir, compensating for any case drain leakage, directly into the piston pump.
Advantages of a Closed Loop Circuit
– Operates efficiently at higher pressures
– Uses less fluid since most is contained within the circuit
– Allows for reversible flow direction
– Replaces lost fluid with fluid supplied by the charge pump
– Provides greater design flexibility for system controls
– Offers precise motor control in a lightweight, compact design
Disadvantages of a Closed Loop Circuit
– Operates at higher temperatures
– Increased risk of fluid contamination
– More expensive to configure and design
– Requires high-pressure hydraulic fluid filtration
Which Circuit Is Best?
Choosing the best Automotive Lift Repair Florida hydraulic pump circuit system depends on your system’s design and intended functions. An open loop configuration is often ideal for systems supplying non-motor actuators, such as cylinders or rotators. On the other hand, closed loop systems may be better suited for wheel and track drive motors on mobile machines and equipment.
In the ever-evolving field of hydraulic systems, it’s crucial to understand the differences between open-loop and closed-loop configurations, as each offers unique benefits suited to specific applications. As a global leader in hydraulic components, our goal is to clarify these distinctions to help you make informed choices for your hydraulic needs.
Open Loop Hydraulic Systems: Simplicity and Versatility
Automotive Lift Repair Florida Open-loop hydraulic systems are defined by fluid flowing in a single direction—from the reservoir to the hydraulic pump, then to the component (such as a motor or cylinder), and finally returning to the reservoir. This setup is known for its straightforward design and ease of maintenance.
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