Hydraulic Accumulator Applications

Examples of various hydraulic accumulator applications in hydraulic systems;

Hydraulic accumulators are used for the following purposes:

Using an accumulator in emergency situations
Compensating for oil leaks
Using a hydraulic accumulator for emergency lubrication
Shortening stroke time
Preventing system failures
Use in pressure fluctuations
Using an accumulator to dampen pressure spikes resulting from on-off conditions
Reducing shock and oscillation
Balancing forces

Examples of Hydraulic Accumulator Applications

Emergency Brakes on Trains

Accumulators can be used in vehicles such as trains, electric trains, cable cars, and automobiles to engage brakes and doors in emergency situations. This way, the energy needed for emergencies is always kept ready in the accumulator.
The control system usually works in reverse — that is, spring force is what operates the brake. Thanks to the accumulators, the brake cylinders remain in the closed position against this spring force.

hydraulic schematic of the emergency brake on trains

Use of Hydraulic Accumulators in Vehicle Suspensions

Mechanical shocks that occur while driving on rough roads or rails can damage the main body and chassis. By using hydro-pneumatic suspension, mechanical shocks can be converted into hydraulic shocks by way of cylinders. The job of the accumulators is to dampen these hydraulic shocks.

circuit diagram of hydraulic accumulator use in vehicle suspension

use of hydraulic accumulator in vehicle suspension

Using hydro-pneumatic suspension in vehicles reduces the risk of accidents. The vehicle’s lifespan increases. Corners can be taken at higher speeds. The load is positioned as desired. Material wear decreases and operating costs are reduced.

Hydraulic Accumulators in Machine Tools

With an accumulator placed directly in front of the user, the inertia of the fluid column is faster than in the case where all of the fluid has to pass through the drive unit. In other words, the system starts operating more quickly. In addition, accumulators meet the user’s varying flow-rate needs.

Hydraulic Accumulator in a Plastic Injection Molding Machine

Shock Damping in Positive Displacement Pumps

Depending on the type of pump, fluctuations can occur in the flow rate. These fluctuations lead to noise and vibration. These, in turn, can damage the hydraulic system.

It’s recommended that shock-damping elements be selected considering the requirements of the equipment, such as high power, short shock duration, and low noise level.

This type of accumulator reduces the flow rate fluctuation created by the machine’s motion, as well as reducing the transfer of the noise from these fluctuations to conducting devices. This lowers the noise level. In addition, the service life of the components and the machine is extended.

example of accumulator use in hydraulic circuits

Shock Damping in Servo Valve Systems

Fast-opening control valves

For control valves (such as servo and proportional valves) to be controlled quickly but smoothly, an accumulator should be placed on both sides of the valve.

It’s also important to avoid negative pressure reaching peak values (which, for example, can damage the pressure filter in the hydraulic system).

Separation of Fluids:

In systems that require 100% separation of fluids, accumulators are used to separate the fluids. The fluids are separated by a bladder or diaphragm placed inside the accumulator.

Separation of Liquids and Gases

Since very large forces are required for hydraulically operated components to function (for example, press cylinders), there’s no need to install a hydraulic power unit up front — starting these components pneumatically and only later switching to hydraulic power is possible.

By using accumulators, hydraulically and pneumatically operated components can be separated from one another. This way, there’s no need to install an additional hydraulic power unit.

Separation of Two Fluids

For example, in floating-ring seal compressors used in the petrochemical industry, the compressed gas inside the compressor must not mix with the sealing fluid, for reasons of contamination and function.

When this type of sealing is involved, this isolated fluid is needed at the seals. The pressure level of this isolated fluid must be between 0.5 and 1 bar, and above the compressor’s gas pressure level.

hydraulic accumulator application examples

A tall tank is mounted above the compressor to maintain high pressure at the sealing zone.

Using an Accumulator as a Spring and for Chain Tensioning

Hydraulic Springs

Hydraulic accumulators can also be used as a hydraulic spring to dampen shock fluctuations.
In these cases, the compressible gas inside the hydraulic accumulator acts as the spring.
Hydraulic spring applications are as follows:

Chain Tensioning

In machines and vehicles, accumulators are used to tension drive chains, to prevent shocks in the drive chain from being transmitted through the system.

Tensioning Power Transmission and Suspension Cables

For example, in cable cars and elevators, the length tolerance of the cables used to ensure trouble-free operation must be low.

By using a hydraulic accumulator, varying cable lengths during the movement of cable cars, or temperature or load changes in elevators, can be compensated for.
This is how the tolerances needed for the desired cable lengths and pulling forces are achieved.