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A few words about

The Complete Book of Airpot - 11558 basicdesign

and operating

principles

How they

All Airpot damping devices are dashpots generically, but for ease of discussion, we identify configurations in which

work

reset the piston for the next cycle (see shock absorberillustration). the piston rod is attached to the load being damped as dashpots. Two Way Damping (Unit damps in both directions.) We identify configurations in which the piston rod is The ball joint rod connection contains no check valve and therefore does not allow air flow through the piston. This results in approximately equal resistance to motion (damp- ing) in both directions. Two way damping is generally notappropriate for the shock absorber con- figuration. struck by — but not attached to the load — as shockabsorbers or snubbers . Either term is acceptable.

The

Whether it’s a dashpot or a shockabsorber, the materials we use are chosen for inherent lubricity, high strength-to-weight ratio, excellent sta- bility under temperature and humidity extremes, close coefficients of thermal expansion, and non-deteriorating performance due to age or non-use. The component parts:•Graphitized carbon piston, precision ground to millionths of an inch TIR•Annealed, borosilicate glass cylin-der. Precision fire-polished bore.

materials

we use

Mounting Stud (Airpot bottom) Fixed orifice In some applications, itmay be possible to use a non-adjustable model. The advan- tages are lower cost and a tamper proof damping setting. These models contain no orifice in the cylinder bottom. Instead, damping rates are achieved by factoryselection of an appropriate piston/cylinder diametral clearance or by factory scribing of the piston to produce a precise leak. Each method provides the leak required to yield a pre-determined damping rate. Please see further discussion under the “Orifice” heading in the “Selection guidelines” section.
Infinitely AdjustableOrificePrecision BoreUltra Low Friction CylinderSelectively MatchedGraphite Carbon PistonBall JointConnecting Rod Vent Path

Damping

Two methods are available to control the amount of damping:

rate

control

push damping. Damping in the extension direction isreferred to as Adjustable orifice All models comestandard with an anti-vibration needle valve built into the dashpot mounting end for damping adjustment.The design allows for screw driver,wrench, or finger adjustment of the adjustment screw. The blunt needlevalve provides capability for a very wide range of continuous adjustment. Adjustable models are the mostcommonly used because they allow a great deal of flexibility in controlling forces or energy levels that can only be approximately known, that may vary from machine to machine, or that may change over time due to machine wear or load variations. Their fine-tuning ability also accommodates any inherent damping variations from unit to unit. pull damping (see dashpot illustration). In the shock absorber configuration, the flexible flapvalve
Dashpot Shock Absorber(snubber) Mounting Stud (Airpot bottom)

Damping

Infinitely AdjustableOrificePrecision BoreUltra Low Friction CylinderSelectively MatchedGraphite Carbon PistonPush Rod Vent Path

control

direction

One Way Damping (push or pull) In dashpot configurations, the piston is attached to the connecting rod by a low friction ball joint or pin link. Depending on the dashpot model, the ball joint will house an internal ball check valve or it will be riveted to a flexible flap valve which is externally mounted on the piston face. Any force applied to the connecting rod which can move the piston will cause air to flow through the pis- ton’s ball check or flap valve with no appreciable restriction (no damping) in one direction and will cause the valve to close in the opposite (desired damping) direc- tion. Damping in the compression direction is referred to as is used, and damping is only available in the pushdirection. Since the push rod is not connected to the load,a low force return spring is provided in the cylinder to
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