The suspended tension backstop is a frame designed by Alfred G. Wheelock for use in baseball. Wheelock's design has been used all over the world in little leagues, high schools, colleges, and professional baseball stadiums. The Baseball Suspended Tension Backstop was also installed free of charge at Milligan College and East Tennessee State University.
Suspended tension backstop Wikipedia
In 1957, in Brooklyn, Los Angeles Dodgers purchasing agent Matt Burns negotiated the terms of the team's first purchase of the frame. Wheelock traveled to the Dodgers training camp in Vero Beach, Florida.
The front of the suspended elastic tension backstop has a netting structure that prevents a baseball or a thrown baseball bat from hitting the framework. Because of this structure, nearby players are less likely to be struck by foul balls and the frame is seldom damaged. Typical backstops use netting tied rigidly to the frame and does not provide the advantages gained by the loose netting of tension backstops
Suspended tension backstops can be shipped and assembled easily because of their lightweight design. The netting can be removed and stored. Modern backstops cannot easily be moved without first removing the net as their netting is often broken and must be patched with canvas reinforcements. The Suspended Tension Backstop framework is constructed of two tubular aluminum structures and adjustable caster wheels. A winch, guy wire cables, and pulleys are used to adjust the height of the roll-down cage. Rubber cables of various sizes are used to suspend the netting and help mitigate impacts.
The netting structure can be removed from the backstop frame in about 5 minutes and replaced in 6 minutes. The folding top can be adjusted to various heights. The netting uses No. 48 cord, and the cable and netting system of suspension and elastic application of this structure make it durable.