Designer's Guide  Shock Absorbers
A shock absorber is a device which converts mechanical energy into thermal energy. The energy transformation occurs as the shock absorber's fluid medium is forced through orifices at high velocities. Selecting a shock absorber is not difficult if you follow the equations in this Guide. To insure adequate sizing, all inputs to the shock absorber must be known or conservatively estimated. For dimensions and capacity of shock sbsorbers go to theappropriate model line on the Taylor Devices Home Page and select the "specifications link." THE END GOAL OF THE EQUATIONS LISTED IN THIS GUIDE IS TO OBTAIN THE ENERGY INPUT TO THE SHOCK ABSORBER, AND THE SPEED AT WHICH IT OCCURS. IF YOU HAVE ANY QUESTIONS, CONTACT OUR FACTORY FOR PROMPT ASSISTANCE. AN IMPROPERLY SIZED SHOCK ABSORBER CAN BE A SAFETY HAZARD. UNITS AND ABBREVIATIONS:(USE ONLY THE UNITS LISTED BELOW IN ALL EQUATIONS IN THIS GUIDE.) KE = Kinetic energy (inlb.) W = Weight (lb.) W_{E} = Effective impact weight (lb.) V = Linear velocity of impact at the shock absorber (ft/sec.) V_{R} = Rotational velocity of impact (radians/sec.) at the shock absorber F = Output force from shock absorber at impact (lb.) F_{D} = Drive force (lb.) H = Vertical height (in.) S = Shock absorber stroke (in.) I = Moment of inertia (lbftsec.^{2}) T = Time (sec.) a = Acceleration (ft/sec.^{2})
PART I  SOLVING FOR VELOCITY OF SIMPLE MACHINERYA. Air Cylinder Drive V = 2 [Average Cylinder Velocity (ft/sec.)] B. Hydraulic Cylinder Drive V = 1.5 [Average Cylinder Velocity (ft/sec.)] C. Machines With Constant Acceleration And Known Time V = aT D. Machines With An Initial Velocity (V_{O}, Ft/Sec.) Plus Constant Acceleration And Known Time
V = V_{O} + aT E. Machines With A Constant Acceleration And Known Distance (Ft.)
To Gain Speed V^{2} = 2 (a) (distance)
PART II  SOLVING FOR KINETIC ENERGYA. Simple Systems 1.Horizontal motion KE = .1865 WV^{2} 2.Vertical motion
KE = W (H + S) 3. Rotary motion
KE = 6 I V^{2}_{R} 4. Applications involving attenuation of complex inputs, such as seismic events, explosions and weapons effects are beyond the scope of this publication. Contact Taylor Devices for assistance when sizing for a complex input. B. Solving For Kinetic Energy Of Overhead Cranes 1.Because of the "slingshot" effect of cablehung loads and overspeed possibilities, effective impact weights, W_{E}, should be used. a. Bridge Buffer W_{E}/Buffer = 1.3 [.5 bridge weight (lb.) + trolley weight (lb.)]  or  W_{E}/Buffer = .5[bridge weight (lb.) + trolley weight (lb.) + lifted load (lb.)] Use whichever weight is greater for kinetic energy calculation. b. Trolley Buffer W_{E}/Buffer = 1.3 [.5 trolley weight (lb.)]  or  W_{E}/Buffer .5 [trolley weight (lb.) + lifted load (lb.)] Use whichever weight is greater for kinetic energy calculation. 2. Solve for kinetic energy per buffer KE per buffer = .1865 W_{E} V^{2}
PART III  SOLVING FOR DRIVE FORCE AT THE SHOCK ABSORBERS
A. A.C. Motors
B. D.C. Motors
** NOTE: Both A. and B. neglect gearing power losses and slippage power losses. C. Solving For Drive Force Of Wind For Outdoor Systems With Known Sail Area In Square Feet
F_{D} = .004 (square feet sail area) (wind speed in mph.)^{2}
PART IV  SIZE SELECTIONA. General Notes On Shock Absorber Selection
B. Selecting The Shock Absorber If Input Is Pure Kinetic Energy With No Motor Drive
C. Deceleration Rate For Your Size Selection
D. Deceleration Time For Shock To Stroke
E. Deceleration Rate For Overhead Cranes
F. Selecting The Shock Absorber If Input Is Kinetic Energy And Drive Force
PART V  THE WSERIES SELFADJUSTING TAYLOR DEVICES' SHOCK ABSORBERThe Taylor Devices' WSeries Shock Absorbers include our UniShoks; our Fluidicshok models 1 x 1 W, 1 x 2 W, 1.25 x 2 W, 1.5 x 3 W; and our Crane Buffer models 1.5 X 3 W, 2.5 x 3 W, 3 x 4 W, 4 x 6 W, 5 x 8 W, 6 x 8 W, 6 x 14 W, 7 x 10 W, 7 x 16 W, and 7 x 20 W. These products are unique in the hydraulics field because their patented Fluidic Amplifiers will adjust shock force automatically to compensate for weight, speed, and drive force variations. When impacted, a WSeries Shock Absorber will instantaneously apply a small test force to the impacting weight. This test force is approximately 1% of the buffer's maximum possible output force. The test force is applied for a distance of 3% of the buffer's stroke. A Fluidic Amplifier inside the shock absorber senses how the application of the test force affects the impact weight, and from this data can determine what the velocity, weight, and drive force to be absorbed actually is. With this information, the Fluidic Amplifier will set the shock force at whatever value is required to absorb the energy within the stroke of the shock. The fluidic circuits necessary to accomplish selfadjustment are built into the piston head of the buffer, and consist of 3 parts, only one of which moves. A. Selection Of A WSeries Or UniShok Shock Absorber
