Hydraulic Dampers | Construction | Working | Different Types

A damper is a shock absorber that is used in an independent suspension system to absorb vibrational energy by resisting motion via viscous friction. Here we will discuss the hydraulic damper and its different types.

Let us take a deep down on Hydraulic Dampers and know more about them.

What Is A Hydraulic Damper?

Hydraulic dampers are damping elements that convert the kinetic energy of moving parts into thermal energy. This avoids hard impacts or excessive vibration amplitudes

Construction Of A Hydraulic Dampers

Hydraulic dampers carry with it a pressure pipe, a connecting rod with a special piston system and also the damping medium of oil, that is why they’re additionally known as hydraulic dampers. At intervals, the oil-filled pressure pipe is that the connecting rod with the special protection and guiding package, that hermetically seals the inside of the hydraulic damper to the atmosphere – even under extreme environmental influences.


Hydraulic Dampers
Source: Ditton

Fig: Shows A Hydraulic Damper

Damping forces:

When the piston rod is moved, the damping medium of oil is pressed through the bores in the piston system. The damping force results from the resistance of the oil when flowing through the piston system. Due to the internal design of the piston system, the pull and push direction can be set independently of each other. The damping forces are dependent on the piston.

Working Principle Of Hydraulic Dampers

Hydraulic suspension integrates rubber springs with a damper system, connecting the front and rear wheel on the same side of the car.

As the front wheel rises over a bump, some of the fluid from its suspension unit (known as a displacer unit) flows to the rear-wheel unit and raises it, so tending to keep the car level.

Types Of Hydraulic Dampers

Below we have listed all the different types of Hydraulic Dampers.

1. Telescopic Direct-Acting Type

This type of damper is directly attached between the body and the suspension component, which moves with the road wheel. The damper is made either as a separate bolt-on unit or as a vital part of a suspension system. Direct-acting dampers are made in single-tube and twin-tube.

It is more reliable and is also cheaper to manufacture. The best performance is achieved when the dampers are installed vertically. However many suspension layouts in use today, specifically those support a live rear axle, install the dampers diagonally so that the stability of the suspension is improved. Dampers are designed to withstand high-speed body roll, therefore do not offer any friction to slow-speed body roll. However manufacturers usually incorporate a transverse stabilizer, often called an anti-roll bar, to control the roll motion.

Sophisticated equipment is available for oscillating the dampers to test their performance. By observing the number of oscillations the spring has to make for the body to come to rest, the effectiveness of the dampers can be ascertained.

1(a). Single-Tube

The operating cylinder of this damper is a single tube, closed at the bottom end by a cap, and joined to an eye or stem for connecting to the moving part of the suspension. A piston, fitted with two-way reed valves, slides in this tube that covers a series of holes through which oil can pass. The piston is connected to a rod, which is attached to the car body and passes through a guide retained at the top of the tube.

The rubber bushes positioned at the attachment points separate road shocks and also permit a light angular movement of the damper body. A rubber seal is held in place by fluid pressure and is installed adjacent to the guide to prevent leakage of fluid. An abutment plate is fitted to the piston to limit the stroke, also provides a flat surface for uniform contact with the top seal during full extension of the damper.

A tubular shield, connected to the rod member safeguards the rod from damage. A chamber at the base of the damper is sealed by a free piston and contains a quantity of inert gas. The gas remains compressed when the damper is completely filled with thin mineral oil.

source: what-when-how

Fig. Single-tube telescopic Hydraulic Dampers

The inner movement of the piston during jounce displaces oil from the bottom to the top chamber. The damping action is provided by the energy needed to pump the oil through the holes as well as to deflect the piston valves. The resistance of each stroke can be altered to suit the requirement by varying the size of the jounce and rebound orifices.

1(b). Twin-Tube

An extra tube is used on this type of dampers to create both a reservoir and an overflow region for the fluid due to rod displacement and expansion. This base valve at the bottom of the working chamber controls

  •  The outward flow of fluid into the reservoir during the joint
  •  The fluid return during the rebound, and
  •  The bleed leakage for reducing the damper’s resistance during slow-speed suspension movements.
Twin tube Telescopic damper.
Source: hydraulics.thesetupwarrior

Fig: Twin tube Telescopic Hydraulic Dampers

2. Lever Type

A lever-type damper is shown diagrammatically in Figure. The damper unit is fastened to the frame and joined by a lever and link to the shaft. The horizontal cylinder uses 2 pistons, that square measure equipped with recuperator and pressure valves. A thin, mineral-base, damper oil is stuffed to the amount of the lowest of the filler plug.

Lever Type Hydraulic Damper
source: what-when-how.com

Fig:lever-type Hydraulic Dampers

The damper pistons square measure operated by the movement of the shaft because of riding over a bump

The movement of pistons displaces oil from one chamber to the other. Oil exert pressure to open the pressure valve, then flows through an orifice to provide resistance, and finally passes through the open recuperator valve to neutralize the depression created in the other chamber. Similar action in the opposite direction is produced during the rebound of the spring. The valve construction and its location are different, and in some designs, the cylinders are mounted vertically.


So we have discussed the hydraulic damper and its types in the above article.

Please share your views about the article in the comment box.