Imagine driving your car around with fixed wheels and no suspension. If it weren’t for the pneumatic tires, it would feel like riding across the grocery store parking lot in a shopping cart. Not only would the ride quality shake the stones from your kidneys, but it would also shake the nuts from your Johnson Rod, if so equipped. Indeed, your vehicle wouldn’t get very far down the road before impacts and instantaneous forces made quick work of wheels, seat frames, and everything in between.
Springs help absorb shock, but also store much of the energy absorbed, only to release it immediately in the opposite direction. The resulting oscillations are often benign, but they reduce precision and increase cycle times in applications that require predictability and repeatability.
Industrial shock absorbers
Shock forces occur in fluid power systems, especially in air and hydraulic cylinders capable of high velocity, as well as in the parts of machinery powered by them. Most manufacturers offer cushions on their air and hydraulic cylinders, which act to rapidly decelerate the load by forcing hydraulic fluid through an orifice over the last inch or so of piston travel. However, in most cases, cushions operate only over the last inch or so of travel and may not have enough time to decelerate the load safely.
The ideal shock absorber slows machine movement at positional extremes to spread forces out over time, lowering peak forces by converting inertia into heat. Engineers must calculate an ideal maximum g load based on mass, velocity, and fragility of the equipment, and then select shock absorbers to achieve the appropriate damping.
Shock absorbers, also called dampers, are essentially linear braking systems. They convert linear motion energy into heat by pushing fluid through an orifice. The smaller the orifice, the more rapid the damping due to increased pressure drop. Many shock absorbers can be tuned by adjusting the orifice size or switching to a different size.
When applications such as presses, high-speed automation, robotics, or material handling experience high shock loads, those forces can damage bearings and bushings, stress structural components, and pose a risk of personal injury. The strain of high impact forces is transmitted through connecting points, pivot joints, fasteners, and welds, slowly degrading them through mushrooming, fissuring, or material fatigue.
Shock absorbers are available in various force capacities, lengths, and damping rates, providing solutions for everything from small material-handling carts to multi-ton coil cars. The ideal shock absorber selection should decelerate the load over the entire stroke length, which should be factored into machine cycle times.
Shock absorbers allow higher-speed operation that would otherwise be limited when the machine deadheads against stops or when the cylinders bump into their heads and caps, both of which are options that reduce machine life. With such disregard for machine function, you can also expect terrifying noises and reduced safety.
If you’re experiencing shock loads on your machine, explore the various shock absorbers available. They often look like miniature cylinders and are available in various mounts to suit any machine, including rigid, trunnion, or clevis styles. Shock absorbers not only improve machine performance but also extend machine longevity, so be sure to specify them for your demanding applications.
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