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Clippard Controls Breathe Life into Astroworld Hippos


(Originally Published on or Prior to 1998)

Clippard Efficiency Tip

A number of circuits involve machine functions or events that take place simultaneously or nearly so.  The normal inclination is to use a single air signal to initiate two or more events at once.  In some circuits this is ok but the experienced circuit designer should be on the lookout for events that are really sequential in nature.

In the example in Fig. 1 below the motor is started and the brake released when the pushbutton is pressed.  In this situation it is possible that the brake will not have released completely before the motor starts thus causing unnecessary wear on the brake and other components perhaps leading to premature maintenance.  It should be remembered that while the arrangement in Fig. 1 may work successfully at a given point in time, conditions change with time and may cause problems.

The simplest solution is to delay slightly (or sequence) the start of the motor giving the brake an opportunity to retract every cycle before the shaft rotates.  This inexpensive addition to the circuit (Fig. 2) assures proper sequence and avoids future problems.

The boat loaded with tourists rounds a bend and heads down a stretch of the “River of No Return,” a jungle cruise type attraction which opened this year as Astroworld Theme Park, adjacent to the Astrodome in Houston, Texas.

Unseen by the passengers, the craft trips a half-submerged limit switch in mid-river and, suddenly, the next series of action begins.  Three hippopotamus break the surface of the water…once lunging toward the boat…once swinging its head…the third rising from the water with jaws agape.

What does this small scenario have to do with Clippard pneumatic controls?


For these hippos, beautifully designed and constructed in the Astroworld Animation Department with lifelike polyurethane foam, do their frightening job thanks to a unique Clippard modular control system.

Early this year, Jerry Evans and Rick Halbrook, Animation Department foreman and lead man respectively, attended a modular circuit design school sponsored by Air-Dreco, Inc., one of Clippard’s Houston distributors.  They worked with Air-Dreco, Inc., one of Clippard’s  Houston  distributors.  They worked with Air-Dreco, Inc., one of Clippard’s Houston distributors.  They worked with Air-Dreco personnel, particularly Larry Wallace, in designing a pneumatic sequence for activation a single hippo that would be a part of the new River of No Return.

The circuit was designed, and refined, and consisted of a 12 valve Clippard module panel.  (Later, two additional hippos were added and the circuit became the present 17 module panel).

As mentioned, the sequence begins when the boat trips a limit switch that is connected by 60 feet of line to the control panel hidden in a grove of trees on the shore.

The largest of the three hippos raises from the water at  an 80 degree angle, blows water out of his nose, opens his jaws, moves forward, closes jaws, lunges toward the boat, then retracts… a total of six movements.

There are four 25 foot, ¼ “ O.D. Clippard urethane hose lines running under the surface from the control box to this largest model.  In addition, there are four 30 foot 3/8” lines running to a nearby 180 degrees actuator, plus a cylinder that helps control the action.

Simultaneous to the above sequence, the second hippo swings his head toward the boat, then back again, while wriggling his ears… a total of three movements.

Here, there are four submerged 35 foot, 1/4'” hose lines leading the “animal” from the control station, plus a 1 ½” bore, one inch stroke Clippard cylinder in the model for the control of ear wriggling. 

The third member of the family simply raises his head out of the water, opens his jaws to maximum width, then slowly submerges again… a total of two basic movements.  However, connected with this hippo is a four station bubble track that lead toward the boat as it passes by, giving the impression of underwater movement.

There are two 15', 3/8” hose lines, plus a cylinder which controls the raising of the head.

The total action sequence controlled by the 17 module circuit is approximately 30 seconds.

In commenting on the use of a pneumatic circuit for such an unusual application, Jerry Evans says, “It is obviously simple to maintain and easier to adjust when necessary.  The modular valve approach offers us maximum versatility, less components to worry about and they are extremely simple to replace if needed.

“There is also the safety factor with pneumatics, since there is no electricity involved.  This is highly important in a tourist installation such as this.  Finally, we saved money with this system, thanks the excellent cooperation of Larry Wallace and the Air-Dreco people.”

Evans added that there’s more pneumatics planned in the near future for the River of No Return.  “We’ll have either a shore-based lion or tiger,” Evans said, “that will operate with Clippard controls.  And, our huge King Kong gorilla, located on shore toward the end of the ride, may eventually become “pneumatic.”

“While he presently simply rolls his eyes at the boat passengers, we’d like to set up a pneumatic circuit to open and close his jaw at the same time.  We can design a new circuit to accomplish this,” Evans said.

The Astroworld Theme Park, one of six operated by the well-known Six Flags organization, opened in 1968 and serves as an important segment of the overall Astrodome area complex.

So this year, when the folks go cruising on the River of No Return, they can thank a well-designed (and well-hidden) Clippard pneumatic circuit for 30 seconds worth of frightening fun.  “At work, home and play Clippard Minimatics will brighten your day”.