Selecting a Forklift Mast - ProLift Toyota

Forklift masts are basic components of a forklift, but depending on your warehouse design, it’s important you have the correct mast type. There are four basic types of forklift masts: standard, duplex, triple stage and quad.

Before purchasing your forklift, whether new or used, research the measurements required for your warehouse and daily operation.

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Forklift Mast Measurements

How High Do You Need to Lift Product?

Identify and measure your highest shelf to determine your lift height requirements. For added safety and efficient product handling, add an extra 6-8 inches to this measurement. This extra space allows a forklift operator additional clearance to lift above the pallet racking and avoid dragging the product as it’s loaded or unloaded.

How Low Should Your Forklift's Lowered or Collapsed Mast Be?

Some forklifts travel in the warehouse and must enter and exit doorways. Perform a walk-through of your building, measuring doorway heights to learn your lowered height requirement. 

If your production also requires forklift operation on trailers, this task can affect forklift mast selection. Learn if your product is delivered in overseas containers, which can be smaller.

If You Load Products Onto Trailers, Do You Double-Stack?

When working in a confined space, two features should be noted – free lift and load backrest. Free lift is defined as the distance the carriage/fork assembly can be lifted without increasing the lowered height. All forklifts have free lift, but some forklift masts have full free lift. This is an advantage when lifting and stacking in trailers.

Forklifts also come standard with a 48” load backrest. During lift the load backrest raises beyond the forklift mast. If your warehouse has height restrictions a modification may be necessary to avoid damage to ceilings, sprinklers, etc.

Forklift Mast Types

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, similar in appearance and function to a standard upright. However, it features a primary, center-mounted cylinder that provides full free lift. This primary cylinder lifts the carriage at a 2-to-1 ratio, raising it to the top of the inner rails before hydraulic fluid is redirected 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 features four sets of rails and an additional set of chains, enabling four stages of lift with full free lift. It operates similarly to a triple-stage upright but includes a second set of chains and pulleys, powered by the secondary lift cylinders, to provide the fourth stage of lift.

Forklift Mast Specifications

A forklift mast has five main components which work together to achieve lift. Forklift operators and service personnel must know the dimensional forklift mast specifications to ensure their equipment’s assembly is not too tall for a work area.

Forklift Mast Operating Specification Terms

Overall Height Lowered (OAHL)

The distance from the floor to the top of the collapsed rail assembly. To learn if the forklift fits through a doorway, check the OAHL.

Maximum Fork Height (MFH)

The distance from the floor to the top surface of the forks with the forklift mast fully extended. This determines the maximum height that loads can be stacked.

Overall Height Raised (OAHR)

The distance from the floor to the top of the carriage/fork assembly with the forklift mast fully extended. This determines the overhead clearance required for full extension stacking.

Free Lift

The distance the carriage/fork assembly can be lifted without increasing the OAHL. All forklift masts have a few inches of free lift so that a load can be raised off the floor. Some forklift masts can provide a full free lift, meaning the forks can be raised to the top of the inner rails without increasing OAHL, an advantage when lifting and stacking in trailers or rail cars, for example.

High Visibility

Term used to describe the “window” an operator has through the forklift mast assembly. The compact, center-mounted primary lift cylinder, and close nesting of rails provides operators with a clear view for loading and stacking operations.

It’s important a forklift’s mast chains are visually inspected by forklift operators every day. ProLift can assist you with maintenance programs, serving your forklift at regular intervals based on operating hours. 

When choosing a new forklift one of the most important considerations is the unit’s maximum lift height and mast type.

An incorrectly specified mast can greatly reduce the forklift’s productivity to the point that a new forklift may need to be purchased.

This week’s blog explains some of the key factors that need to be considered when selecting a forklift mast, whilst also profiling the four main mast types available.

Factors to Consider When Selecting a Forklift Mast

Lift Height

Also commonly referred to as maximum lift height, this is the height of the forklift tynes when the mast is fully extended.

When choosing a lift height it is recommended to add additional lift height beyond the highest point of racking to ensure the forklift is able to safely adjust loads at the top of racking.

An important consideration when selecting a masts lift height is that the higher the mast is extended in the air the lift capacity of the forklift may decreases depending on the load center of the mast.

This is to ensure the load remains stable when being lifted reducing the potential for the load to fall of the tynes and causing injury or product damage.

Lowered or Collapsed Height

This is the height of the mast from the ground when the tynes are fully lowered.

It is imperative to consider the masts collapsed height especially if the forklift has to travel through doorways or under raised walkways.

If the masts lowered height is too high it may hit doorways or the raised walkways causing the unit to remain stuck in or under the doorway or walkway or cause significant damage to the mast, doorway or walkway.

Lowered mast height is also important for forklifts that are used to unload containers so they can safely fit inside, this in conjunction with free lift is explained further below.

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Free Lift

Free lift is the height a load can be lifted before the mast begins to extend upwards.

Free lift is very important for forklifts that operate in confined spaces where overhead clearance is limited such as in shipping container as mentioned above.

Masts that have no free lift will begin to extend upwards straight away as the forklifts beings lifting, whereas a mast with full free lift will allow the tynes to lift to the top of the inner section of mast before extending upwards.

Load Backrest

The majority of forklifts come fitted with a 48 inch load backrest for loads to safely sit up against when resting on the tynes.

Depending on the loads being lifted with the forklift a specialised backrest may need to be installed to prevent damage to the items being lifted.

Common Forklift Mast Types

Single Stage Mast

The most basic of masts that has only one mast channel offering limited lifting height.

They offer no free lift and are best suited to low level simple applications where overhead clearance isn’t an issue such as lifting loads from the bed of trucks outside.

Two-Stage Mast

Also known as a duplex mast they are the most common mast setup for forklifts operating in warehouses.

They’re commonly used for single and double stacking of loads into high racking such as freight and logistics or the delivery of manufactured goods.

The mast consists of two sections with the inner section elevating the carriage and tynes, this offers limited free lift as the outer mast section does not extend till the tynes have reached the top of the inner section.

With the hydraulic cylinder located in the center of the mast and only two mast sections two-stage masts offer operators greater forward visibility as there are less components and sections in the way disrupting the view.

Three-Stage Mast

Also referred to as a triplex mast, three-stage masts offer the greatest versatility and is ideally suited for application where loads must be lifted extended heights or where overhead clearance is an issue such as in containers.

Similar to a two-stage mast the hydraulic cylinder sits in the middle of three masts sections.

The height of three stage masts does not extend beyond the top of the forklift operator cabin, they’re ability to lift loads extended distances comes from the extra section of mast, this make triplex masks the ideal solution for unloading containers where overhead clearance is an issue.

Another reason why they’re ideal for use in unloading containers is that they offer full free lift where the tynes are able to fully rise to the full height of the inner mast section before the outer sections begin to rise to lift the loads higher.

As well as forklifts triplex masts are often installed onto reach trucks as they can further extend the lift height to be able to store goods at greater heights.

The additional mast section does slightly reduce the amount of forward visibility for operators as there are more sections.

Four-Stage Mast

Also called quad masts this more complex mast with four sections relies upon four sets of rails and chains to lift loads in very high stacking operations in specialised industries.

Operators of quad mast forklifts need to undertake advanced training due to the potential limited visibility of loads when they are lifted to great heights.

Just like triplex masts quad masts offer full free lift.

This week’s blog has demonstrated some key factors to consider when selecting the right forklift mast for your application as well as showcasing the four main types of masts available in today’s market.

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