Accumulators And Gas Bottles

March 6, 2008
In operation, hydropneumatic accumulators use compressed gas to apply force to hydraulic fluid.

Piston accumulators have a cylindrical body, sealed by a gas cap and charging valve at the gas end, and a hydraulic cap at the fluid end. A lightweight piston separates the gas and hydraulic sides. This design offers high efficiency and flexibility in most applications due to availability in a wide range of sizes. Application advantages include:

  • High flow rates.
  • Wide temperature range.
  • High compression ratios.
  • Withstands off-road abuse.
  • Almost unlimited size and mounting possibilities.
  • Works well with gas bottles.

Bladder accumulators feature a nonpleated, flexible rubber bladder housed within a steel shell. The open end of the bladder attaches to the precharging valve at the gas end of the shell. A poppet valve, normally held open by spring pressure, regulates fluid flow through the hydraulic port. Application advantages include:

  • Suitable for most applications.
  • Dirt tolerant.
  • Quick response.
  • Works well with water and low-lubricity fluids.

Gas bottles are pressurized metal cylinders that connect to the gas side of an accumulator with metal tubing. Thus, gas bottles can mount some distance away from the accumulator and in any orientation — offering flexibility to the machine designer. They work by increasing the gas capacity of small accumulators, in many instances letting the combination replace larger accumulators. This tends to reduce costs, save space and weight, and require lessexpensive seals. An added advantage is that gas bottles seldom require maintenance.

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