ACE Controls Main Catalog - ACE - #8

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6 ACE Controls Inc. · 800-521-3320 · (248) 476-0213 · Fax (248) 476-2470 · www.acecontrols.com · email: shocks@acecontrols.com Force Stroke Force Stroke High Effective Weight Example 2: Orifice Area Is Too Large (High Set-Down) Linear Deceleration Low Effective Weight Example 1: Orifice Area Is Too Small (High On-Set) Linear Deceleration Low Effective Weight High Effective Weight 5 lbs (2. 27 kg) 25 ft/sec (7.62 m/s) 50 lbs (22.68 kg) 0.5 f/s (0.15 m/s) 800 lbs (111 N) Effective weight is an important factor in selecting shock absorbers. A shock absorber “sees” the impact of an object in terms of weight and velocity only; it does not ”see” any propelling force. The effective weight can be thought of as the weight that the shock absorber “sees” on impact. Effective weight includes the effect of the propelling force on the performance of the shock absorber. Failing to consider the effective weight may result in improper selection and poor performance of the shock absorber. Under extreme conditions, an effective weight that is too low may result in high forces at the start of stroke (high on-set force). However, an effective weight that is too high for the shock absorber may cause high forces at the end of stroke (high set-down force). Consider the following examples: 1.) A 5 lb (2.27 kg) weight travelling at 25 ft/sec (7.62 m/s) has 625 lbs (71 Nm) of kinetic energy (figure A). On this basis alone, a MA 3325 would be selected. However, because there is no propelling force, the calculated effective weight is five pounds – which is below the effective weight range of the standard MA 3325. This is a high on-set force at the start of the stroke (Figure B). The solution is to use a speciallyorificed shock absorber to handle the load. 2.) A weight of 50 lbs (22.68 kg) has an impact velocity of 0.5 ft/sec (0.15 m/s) with a propelling force of 800 lbs (111N) (Figure C). The total impact energy is 802.5 inch-pounds. Again, a MA 3325 would be selected based just on the energy. The effective weight is calculated to be 16,050 pounds (7,280 kg). This is well above the range of the standard MA 3325. If this shock absorber is used, high-set-down forces will result (Figure D). In this case, the solution is to use a ML 3325, which is designed to work in low-velocity, high-effective weight applications. Figure A Figure B Figure C Figure D By combining application data with a shock absorbers design parameters, ACE engineers can create a picture of how the shock will perform when impacted by the application load. Peak reaction force, peak deceleration (G’s), time through stroke, and velocity decay are identified with extreme accuracy. The user benefits by having the guesswork taken out of sizing decisions and by knowing before installation how his shock problem will be solved. Simulation is also used to maximize the performance of ACE adjustable models by predicting the ideal adjustment setting for a particular group of conditions. By using simulation software during product development stages, ACE has maximized the performance of its entire line of deceleration devices for over two decades. Computer-Aided Simulation Effective Weight