 
SM-4 Sanivan (1950-1958) 
A fleet of SM-4 Sanivans at Watertown, New York in 1953 (Sicard Photo) The SM-4 Sanivan was another design from Ronaldo Boissonnault, replacing the SM-3 in the early 1950's. The patent was filed in March, 1950, and production likely commenced shortly thereafter. The tri-panel folding ejector remained the same as the SM-3, but a big change came in the form of a new packing panel, which now travelled completely within the side walls of the tailgate structure. The gear and sector driving the packing panel was also eliminated, exchanged for a more direct rod and crank arrangement. The new tailgate design is shown in the diagram below. 
Loading Position Packing panel 1 rests on floor of tailgate structure, and includes curved vertical section 5, reinforcing braces 6, and pins 3 which protrude through side walls. Packing panel assembly forms trough, pivotable on bearing 7. Retainer panel 2 is pivotable on bearing 10, and rests in lowered position effectively blocking passageway into body. Refuse A is loaded on to surface of packing panel assembly. First Stage Operator commences cycle by pulling and holding control lever for packing panel 1, causing rotation upward through the hopper. Hydraulic cylinders (not shown) pull pins 3 upward through arcuate slots in side wall 4, while packing panel assembly pivots into cavity 8 within tailgate. As the packing panel rises, the load A is squeezed against the rear face of retainer panel thereby crushing bulky items.2. When maximum pressure is achieved (a hydraulic pressure gauge was provided), packing panel stops, and the lever is then released. Second Stage Operator next pulls lever controlling retainer panel 2, which raises the panel and opens the passageway from the hopper to the storage body. The packing panel 1 is then further actuated, pushing the pre-crushed load A into storage body until it reaches it's maximum travel limit. Lever is released, which stops packing panel in this position. Final Stage Operator reverses retainer panel 2, thereby closing off passageway and scraping the forward face of packing panel 1. Compacted load is now retained in body, and packing panel may be reversed through hopper to the loading postion. SM-4 Exterior Components Side view at left shows tailgate with inspection covers removed, revealing packing panel cylinders 12 which act against bellcrank 13, which in turn pulls rod 14 connected to packing panel assembly at pin 3. The broken line drawing (light green shaded) shows the cylinder and linkage in the "packing panel raised" position, with travel following path of slots 4. Much like the SM-3, cylinders 15 directly pivot retainer panel shaft using short bellcranks 16, shown in panel open/closed positions. A sliding closure door 17 seals off hopper opening, and was designed to be closed during packing cycle. As previously noted, a hydraulic oil pressure gauge was mounted on the tailgate (not shown) to indicate when individual panels had reached maximum travel. 
11/6/04 © 2004 Eric Voytko All rights reserved Photos from factory brochures/advertisements except as noted Logos shown are the trademarks of respective manufacturers |