To avoid this, Watt added the parallelogram linkage BCDE to form a pantograph.
2.
The most common version replaces the arm linkages with two independent parallelogram linkages, with a pair of light tension springs on each half of the arm.
3.
The transaxle design, in combination with a Watt's parallelogram linkage, inboard rear brakes and a well-located de Dion rear suspension, resulted in excellent traction and handling.
4.
On December 18, 1962, the CAB published its final report on the accident, concluding that the probable cause was " . . . the loss of an AN-175-21 nickel steel bolt from the parallelogram linkage of the elevator boost system, resulting in loss of control of the aircraft ."