How Does A Pneumatic Shock Absorber Work?

When the piston reaches the end of its stroke, pneumatic shock absorbers work to help reduce load rebound and minimise shock to both the load and its connected equipment. This form of mechanical cushioning helps to reduce the impact of the piston rod against the end cap. 

Shock absorbers are used in a wide range of applications to cushion both linear and rotary movements, as well as sliding, rolling, or free-falling motions. They are engineered to endure harsh conditions, resisting contamination, corrosion, and fluctuating temperatures. You will often find them in high-cycle machinery, such as automated stamping presses, where they significantly reduce metal-on-metal impacts. This reduction in impacts leads to fewer equipment failures and lower maintenance costs.

How Pneumatic Shock Absorbers Work

You can stop a load smoothly in a variety of ways, including using a compression spring, a rubber snubber or a dashpot. Each of these can decelerate the piston rod and absorb its kinetic energy. With the spring or snubber options, this energy is stored in the compressed rubber or spring, which rebounds when it decompresses. Dashpots work by means of a fluid-filled cylinder, which resists the force of the piston rod, releasing the fluid gradually as the piston retracts. 

The problem with these three methods of energy dissipation is that they react at different rates according to load vs resisting force calculations. The most effective way to stop a moving object is to decelerate at a steady rate, using a constant resisting force to gradually slow it down until it comes to a complete stop. This linear deceleration is provided by pneumatic shock absorbers, which convert the load’s kinetic energy into heat. This heat is then dispersed into the atmosphere. They don’t rebound or transmit shocks onward to connected equipment. 

The moving load drives the piston rod forward, forcing fluid in the cylinder through openings in its inner wall. The restriction in fluid flow creates the resistance force, which decelerates the piston at a uniform rate until the kinetic energy is all gone. Fluid pressure in a shock absorber is constant, as is resistance to the load. Removing the load drives the piston back to its extended position by means of the return spring. 

Choosing The Right Shock Absorber

The most important consideration in selecting a pneumatic shock absorber is what type of load is being stopped. These may include simple inertial loads, rotating or free-falling loads, or loads with an additional force applied. You also need to consider the load’s weight and velocity to determine what size you need, as well as how often it will impact, whether it will transmit that shock to other equipment and what its ambient operating conditions are. 

These might include extreme temperatures, maximum propelling force, load acceleration and time limitations like minimum and maximum cycle times. You should factor in how long it takes between strokes for the piston to return to the extended position and the cycle rate. A shock absorber will overheat if it has to handle too many impacts in a given cycle, reducing the fluid’s ability to absorb the energy and causing potential failure.

You must mount your shock absorbers securely to a rigid mounting structure, with an external stop to provide a solid anchoring point. This will prevent the shock absorber piston from levelling off as it ends its deceleration stroke, causing damage to the shock absorber itself or any attached equipment. The shock absorber may come with its own mounting flange, or you can secure it to the cylinder with a stop collar or jam nut. Their bolt-on design means you can easily retrofit pneumatic shock absorbers to your existing equipment. 

Why Do You Need Pneumatic Shock Absorbers? 

The impact forces in an industrial environment are numerous and constant, coming from various machine actions, such as heavy presses, conveyor systems, or fast-moving pneumatic actuators that move robotic arms. These shocks can eventually cause serious damage to equipment unless they’re properly cushioned. 

Pneumatic shock absorbers solve this problem by absorbing and dissipating the kinetic energy of the cylinder’s piston. This reduces the impact of stresses on both the piston and cylinder, as well as the other machinery in your pneumatic system. As they work solely by the force of air pressure, pneumatic shock absorbers don’t require any external power or complex wiring.