What type of mast do you need for your forklift?
This may be a question posed to you during your next forklift purchase. Understanding the types of masts available and what each can do is helpful for selection. Below ProLift has defined the four basic types of uprights and masts: standard, duplex, triple stage and quad.
4 Types of Forklift Masts
Standard Upright (Simplex, V Mast)
The standard upright is a two-stage assembly with two rails, one stationary and one movable inner rail. This upright uses two side-mounted lift cylinders to provide direct lift to the inner rails and indirect chain lift to the carriage/fork assembly. The chain raises the carriage at a rate of two inches for every inch of cylinder rod extension.
Duplex Upright (Full Free Lift, FFL, Hi-Lo, FV Mast)
The duplex upright is a two-stage assembly with full free lift. This upright resembles the standard upright and works in the same way, except a primary, center-mounted cylinder provides full free lift. The primary cylinder also raises the carriage at a 2-to-1 ratio, but raises the carriage to the top of the inner rails before hydraulic fluid is rerouted to the side-mounted secondary cylinders for direct rail lift.
Triple Stage Upright (Triplex, Triple, TSU, FSV Mast)
The triple stage upright uses three sets of rails, two movable rails and one stationary rail for three stage lift with full free lift. The same principles of operation apply in triple-stage lift as the hi-lo model but with an extra stage of lift. The primary cylinder provides the full free lift of the carriage and forks. The secondary lift cylinders are attached to the intermediate rails. When these cylinders begin lift, they lift the intermediate rails directly while the chains pull the inner set of rails along with the carriage/fork assembly.
Quad Upright (QFV Mast)
The quad upright uses four sets of rails and an added set of chains to provide four stages of lift with full free lift. Quad uprights work basically in the same way as triple stage uprights except in that a second set of chains and pulleys operated by the secondary lift cylinders provide the fourth stage of lift.
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