Mitre Gate Moving Machine
or
Bullwheels and Motors

The movement of a gate leaf is accomplished through a huge connecting rod, one end of which is attached to the leaf about midway between the wall and the other end of the leaf; the other end is attached to a huge master wheel which lies flat on the top of the lock wall.  This master wheel weighs 34,000 pounds and turns on a huge center pin which is keyed in a heavy casting, anchored securely to the concrete.  The casting and the center pin weigh 13,000 pounds.  The rim of the great master wheel is so heavy that its weight would break the spokes, and so it is supported in four places by rollers.   One-half of this rim is cog geared.  Through these it is revolved by an electric motor which drives a train of gears and pinions.  These turn the rim of the wheel, which moves the connecting rod to the gate, causing the gate to open or close in two minutes.  The action is just the reverse of the action of the connecting rod on the driving wheel of a locomotive.  If the reader can picture a locomotive suspended in the air, and the driving wheel moved by power applied to the rim, the resulting movement of the connecting rod with the piston will represent in general outline the method by which the gate leaves are moved back and forth.  The motor is remotely controlled by an operator stationed in the controlling house near the lower end of the upper locks, a simple pull of a small switch being sufficient either to close or open a 700-ton gate.

Read more:  History of the Panama Canal by Ira E. Bennett, Historical Publishing Company, Washington, D.C., 1915

NOTE:  The Panama Canal Authority is in the process of changing over to a hydraulic system and new motors.

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Installing Bullwheels and Motors

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Discarded Bullwheel halves at Miraflores Locks

Photos: Print Ad Wheeling Mold & Foundry
I. L. Maduro, Randy Everson

More Pictures

CZBrats
June 15, 2001