Question 2: What stroke shock absorber should I use ?

Answer: The stroke equates to the distance over which the mass is brought to rest and therefore it directly relates to the deceleration rate. It is generally best to select the longest stroke you can accommodate as it provides the maximum absorption and lowest deceleration rate, at a minimal additional cost.

Generally to stop a mass within an acceptable deceleration:-
For impact velocities below 1 m/s strokes 5 mm to 50 mm are typically selected.
For impact velocities above 1 m/s strokes 25 mm to 400 mm are typically selected.

Question 3: What is Effective Weight ?

Answer: The effective weight of an application is the weight that the shock absorber “sees” impacting it. The effective weight seen by the shock absorber is a combination of the actual moving mass and the propelling force driving the mass. Calculating the effective weight is a major factor in determining the selection of the correct shock absorber and can determine the optimum adjustment setting to achieve true linear deceleration.

Question 4: Should I use an adjustable or self compensating shock absorber ?

Answer: Adjustable shock absorbers can be set most accurately to suit the effective weight of an application, consequently reducing the peak reaction force to the minimum. Adjustable shock absorbers are best suited to an application where the mass, propelling force, impact velocity and cycle rate remain constant.

Self compensating shock absorbers are well suited when a pair or more are impacted in parallel. Self compensating shock absorbers are designed to work within a variable range of effective weight when the application mass, propelling force, impact velocity and cycle rate can vary.

Question 5: How do I adjust my shock absorber?

Answer: The adjustment has a graduation scale from 0 to 9. The shock absorber is delivered set at 5. If there is a hard impact at the start of the stroke - adjust the absorber softer i.e. towards the 9 on the scale. If there is a hard set down at the end of the stroke - adjust the absorber harder i.e. towards 0 on the scale.

If the adjustment is approaching “0” on the scale this means:
a) The impact velocity is too low: consider changing to a low velocity type shock absorber or:
b) The shock absorber selected is too small: use the next size larger or mount two absorbers in parallel.

Question 6: How do I know my shock absorber is correctly adjusted at the right setting?

Answer: Ideally if you can feel or measure the reaction force about the fixing at the rear of the shock absorber, you can determine the lowest reaction force, which is when the shock absorber will be correctly adjusted.

However if for safety reasons this is not practical when you look at the shock absorber being impacted and going through it’s stroke coming to rest at the end, it is correctly adjusted when this most appears to look like a skilled sportsman catching a ball. The load should be brought smoothly to rest through the full stroke of the shock absorber. There should be no abrupt changes in velocity during the stroke 

Question 7: What modifications and protective coatings can be used in aggressive application environments ?

Answer: Many of our shock absorbers can be fitted or modified with, side load adapters, air knife collars, special rod seals, metal scraper rod seals, steel shrouds, special material rod seals, additional chrome plating on the rod, stainless steel rods, springs or complete stainless steel shock absorbers. Many of our shock absorbers can have their external components coated with Zinc, Nickel, Epoxy marine paint, Dacralyte paint, weartec plus impregnation and many of our customers specified paint systems.

Question 8: How long will my shock absorber last ?

Answer: Most applications fall into three categories:           
a) Infrequently used but sometimes installed in a remote or aggressive environment. In most cases adequate selection of the available modifications and protective coatings and perhaps an inspection every 5 years by Ace has provided many ten’s of years use on-site for some applications.

b) Very high cycle rate use on modern production systems. The initial calculation, selection, sizing and installation is essential to achieving high cycle life from the shock absorbers in these production systems. Many million of life cycles can be achieved with help from the Ace Controls Technical support team throughout the World.

c) Moderate cycle rate use on a variety of applications. The selection and installation are not as critical and protection from the application environment has played an equal part in providing many years of maintenance free cycle life.

Question 9: What can shorten shock absorber life ?

Answer: Over the years we have supplied shock absorbers in many applications here are a few aggressive materials or actions we have provided solutions to increase our absorbers life cycle: Side load, submersion in radio active waste, Submersion and pressurisation sub sea, pressure wash down, extraordinary impact force or velocity, localised welding heat or splatter, accidental spillage of paint or corrosive fluids on the rod or rod seals internal ingress of: Tea, tabacco, sand, pastry, petroleum based cutting fluids, toxic and sulphurous gases, textile dust, paper dust, metal swarf, grinding dust, Ice cream, vinegar, glass, wool, fibre glass, battery acid and wood dust.

Question 10: What happens when I only use part of the shock absorber stroke ?

Answer: You can use only part of the stroke however it is important to try and use the last part. This is because If you use part of the stroke up to the end of the stroke you will get a linear deceleration effect bringing the mass close to rest, you will not however be able to utilise the full energy capacity available or the lowest deceleration rate.

You may find it more akward to adjust the shock absorber and in some cases the mass may bounce back. If you use the first part of the stroke, but partially stroke not to the end, you will not get a linear deceleration effect and will find it very difficult to adjust or invariably the mass will bounce back.

In all application cases where you need to only use part of our standard stroke length consult with Ace, we can modify standard shock absorbers to effectively partial stroke with stop tubes, custom orificing and special hydraulic fluids.

Question 11: What happens when shock absorbers are used in very high ambient temperatures ?

Answer: When used in ambient temperatures above our quoted limits, the hydraulic fluid starts to break down, the encapsulated air in the return accumulator expands above it’s design volume then eventually the rod seals start to melt and the shock absorber loses its fluid. During this cycle of catastrophic events the efficiency of the shock absorber to function deteriorates towards it’s final inevitable failure.

Ace has a range of high temperature shock absorbers available just for applications with high ambient temperatures, please consult Ace we can help you select the best available solution for these difficult environments.

Question 12: What happens when shock absorbers are used in very low ambient temperatures ?

Answer: When used in ambient temperatures below our quoted limits, the type of particular hydraulic fluid and it’s characteristic to viscous change, due to temperature change, will be the key criteria in how able the shock absorber performs.

Ace can select the most temperature stable hydraulic fluids and then run simulation performance curves at your particular application criteria and low ambient temperature to investigate the predicted deceleration capability, efficiency and adjustment setting or self compensating suffix required, please consult Ace we can help you select the best available solution for these difficult environments.

Question 13: What is the fastest impact velocity an Ace shock absorber can repeatable accept ?

Answer: Specially calculated, selected, sized and simulated for performance with internal modifications to the orificing and component materials an Ace shock absorber can be designed to accept an impact velocity of up to 25 m/s.

Question 14: The catalogue shows MC150 units operating up to 25 million cycles, with a larger unit such as a MA3325 what cycle life can I expect ?

Answer: It is not possible to give a definitive answer to this, as each individual application  is different to the rest. If the unit has been correctly sized for that particular application then more than a million plus cycles can be achieved but ultimately it is dependent on how the shock absorber is being used and, equally important, in what environment it is working.

Question 15: How does the construction of your shock absorbers differ from some of your competitors ?

Answer: At ACE we build our units with closed end/ one piece bodies and inner pressure chambers which greatly reduces the chance of sudden failure or machine damage in the event of an overload. Whereas, some of our competitors manufacture using bodies and inner pressure chambers made from tube stock, with internal parts held in by a snap ring which, in turn, takes all the load and can fail suddenly with catastrophic results.

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Question 16: With the “VC” Precision Feed control units, why when some applications are situated in lubrication or cutting fluid environments, are the seals made from EPDM material and not from Neoprene material ?

Answer: It is true the harder Neoprene material will last longer in petroleum based environments; however, the EPDM material will give a much greater life expectancy due to its flexibility in a clean dry environment. By utilising the SP25 Air Bleed Adapter on the VC2515 to VC2555 feed control units the standard EPDM seals should be protected against the petroleum based fluids giving the greater life expectancy.

Question 17: How easy is it to adjust your HB dampers ?

Answer: To adjust the travel speed, pull (or push) the piston rod to its fully extended (or fully compressed) position. Whilst still pulling the rod turn it clockwise to increase damping anti-clock wise to decrease the damping. The adjustment is multi-turn and may require several trial and error adjustments. This adjustment can add up to 6 mm to the L dimension shown in the catalogue drawing.

Question 18: Do Ace gas springs have to be mounted in the "rod down" position ?

Answer: No, the gas spring can be mounted in any position, but, to take advantage of the built-in end position damping it should be mounted in the rod downwards position. It is the oil zone which provides this damping at the fully open position to avoid impact damage.