Silentpack The Silent Hoist Winch & Crane Company Brooklyn, New York by Eric Voytko     Scottish-born brothers Albert and William Hulley were New York inventors who filed a group of patents for truck equipment in the early 1930s, including a power-operated tailgate for refuse trucks that automatically opened as the body was hoisted. In 1932, they developed a circular refuse body, which featured a gear-driven impeller that both compacted and ejected the load. The impeller blade was more like a 'warped piston', which was threaded into a spiral groove within the body. The periphery of the impeller was lined with gear teeth which engaged the groove, and were enmeshed with pinion gears spaced all along the top of the body. These pinions were connected by a common shaft and driven via the truck PTO. In operation, the impeller both rotated and moved rearward to compress the load. As the ring gear lost contact with the driving pinion, it engaged the next pinion along the top shaft until it reached the end of the body. The shaft was reversed to return the impeller to the front of the body for the next load. Ejection was accomplished by opening the end gate and pushing out the load.     The example seen here was built by Silent Hoist & Crane of Brooklyn in 1937, and called Silentpack. The company specialized in container handling equipment and forklifts, and this is the only known refuse body the company produced. The images here seem to document a test performed by the New York Department of Sanitation (DSNY), with dump trucks discharging their contents on to the ground, which were then fed into the Silentpack body. The company claimed the contents of a 24-yard enclosed truck were compressed to fit within one-half of the 12-yard circular body. The same year, the DSNY would adopt escalator-loaders for their fleet, which probably doomed the Silentpack. Silent Hoist remained in business through 1994, when Illinois-based Hoist Liftruck acquired the rights to build their line of cushion-tire forklifts.     Side loading doors opened for loading. Thee would be closed prior to activating the impeller. The partial marking "274-" is visible at right, indicating this truck was likely owned by the New York Sanitation Department (DSNY).     A scow-type dump body of unknown capacity unloads its contents on the pavement, which are then hand-loaded into the Silentpack. The refuse was compressed in a third of the 12-cubic yard circular body.     Another test, where the contents of this 24-yard enclosed dump body were compacted into half of the Silentpack. Note the heavy reinforcement of its tailgate, to withstand the packing stresses The truck body weighed in at 8,000 pounds empty. The truck at right features the Hulley-designed automatic tailgate. REFERENCES American City Magazine, September 1937, page 137: New Refuse Body Packs and Dumps Horizontally 1940 Census data SELECTED PATENTS Patent # Description Inventor Assignee Date US1961587 Self-Loading Truck Hulley, et al May 13, 1932 US1872738A Tail Gate Control Device Hulley, et al April 20, 1931 US1892149A Sliding Door Clamp Hulley, et al April 20, 1931 5/22/22 © 2022 All Rights Reserved Logos shown are the trademarks of respective manufacturers Photos from factory brochures/trade advertisements except as noted