Why the Design changed Lowering forks- disengage trays at ground position Locking/releasing forks at ground position Improve ergonomics

3 way valve opens to pressure line Start Air goes into cylinder 3 way valve opens to pressure line Forks lower Dolly and trays loaded Forks lock Is switch activated Restart Process Is valve switched to open position No Yes No Yes Forks raise to home position

Adjustable needle valve 3 way valve Air from line Muffler Air regulator Adjustable needle valve Emergency relief ball valve Air cylinder (2 inch bore and max of 125 lbs to lower requires ~40psi)

5th has been placed and is descending Line is unpressurized 3 Way Normally Open to Atmosphere Push-Valve

5th tray has fully descended Line is pressurized Switched pressed, wheels on ground

Piston Pressurized, lowering piston slowly Forks lower, trays in contact with floor only

Filled until 40 psi is reached and cylinder is locked in down position

Open to ATM closed to pressurized line Compressed air released to ATM

Piston raises, acting as air damper Open to ATM again

http://www.grainger.com/Grainger/PARKER-Manual-Air-Control-Valve-3FED8 http://www.fremontindustrialsupply.com/servlet/the-12148/STC-3R210-dsh-1-fdsh-4-dsh-M-3-way/Detail http://www.mcmaster.com/#standard-air-cylinders/=l5ib4t