Forklift Jargon Buster | Kelvin Engineering

Reading A Forklift Spec Sheet

What is load centre?

Load centre is the distance from the front of the forks to the middle of the load — usually measured at 500mm as standard. It matters because a forklift's capacity is only true at that distance. A truck rated to lift 1000kg will lift less than that if the load is bulkier or sits further forward on the forks. If you're moving long or wide pallets, this is the number to check before assuming a forklift "can't" handle your job.

What's the difference between rated capacity and maximum capacity?

Rated capacity is the safe, certified weight a forklift can lift at the standard load centre — this is the number on the spec sheet and the one to trust. Maximum capacity sometimes appears on marketing material and refers to a best-case scenario that may not apply to your actual loads. When comparing forklifts, always compare rated capacity at the same load centre, not headline numbers.

What's the difference between lift height and closed height?

Lift height is how high the forks can reach with the mast fully extended — this is what determines whether you can reach your top shelf. Closed height is how tall the forklift is with the mast lowered — this is what determines whether it fits through your doors and under any low ceilings or beams. A forklift can have a tall lift height and still have a low closed height, which is often the more important number for tight buildings.

What is turning radius?

Turning radius is the smallest circle a forklift needs to complete a full turn. A smaller turning radius means the forklift can manoeuvre and turn around in narrower spaces — useful in tight warehouses, between racking, or near loading bays where there isn't room to swing wide. Wheelbase, the distance between the front and rear axles, has a knock-on effect here too: a shorter wheelbase generally means a tighter turning circle.

What is aisle width?

This is the minimum aisle width a forklift needs to pick up or put down a pallet at 90 degrees to the racking — turning in from the aisle, placing the load, and reversing back out. It's one of the most important numbers for small warehouses, because if your aisles are narrower than a forklift's stated aisle width, that forklift simply won't work in your space, regardless of how good its other specs are.

What's the difference between a ride-on and a pedestrian forklift?

A ride-on forklift has a seat and the operator drives it sitting down, similar to driving a car. A pedestrian (or "walk-behind") forklift is steered by an operator walking alongside or behind it using a control handle. Pedestrian models are generally smaller, cheaper, and suited to lighter, more occasional use; ride-on models suit frequent, all-day use where speed and operator comfort matter more.

What's the difference between a counterbalance, reach truck, and stacker?

A counterbalance forklift has its weight built into the chassis to balance the load on the forks, allowing it to drive right up to a pallet without extra support legs — it's the most familiar "classic forklift" shape. A reach truck has extending forks and support legs either side of the load, designed for very narrow aisles and high racking, mostly used in large logistics warehouses. A stacker is a simpler, lighter machine — usually electric and either pedestrian or ride-on — designed mainly for lifting and stacking pallets rather than heavy-duty general use. Most small and medium warehouses are better served by a compact counterbalance or a stacker rather than a full reach truck.

What's the difference between an open or closed bottom pallet, and does it matter which forklift I use?

A closed bottom pallet has a solid base with no gaps, so forks can only enter from the top. An open bottom pallet has gaps between the bottom boards, allowing forks to enter from either the top or the underside. For most of our range this doesn't affect which forklift you need — but it does matter for the KES-15 powered stacker, which is only suitable for open bottom pallets. If you're mainly handling closed bottom pallets, choose from the rest of our range instead.

The Mast & Lifting Bit

What is a mast?

The mast is the upright frame at the front of the forklift that the forks travel up and down. It's made of interlocking steel rails, with hydraulic rams doing the actual lifting. When people talk about lift height, closed height, or duplex versus triplex, they're describing different versions of this same component.

What is a duplex mast?

A duplex mast has two stages, or sections, that extend to reach full lift height. It's the standard mast type on most forklifts and offers a good balance of lift height, visibility, and cost. If a spec sheet doesn't mention the mast type, it's usually duplex.

What is a triplex mast?

A triplex mast has three stages instead of two, letting the forklift reach a greater lift height while keeping the same closed height. This makes it the better choice when you need to reach high racking but still have to fit through standard doors or under low ceilings. Triplex masts typically cost more than duplex and have a small trade-off in visibility, since there's an extra rail section to see around.

What is free lift, and what is a free lift mast?

Free lift is the height the forks can rise before the mast itself starts to extend upward. A free lift mast is designed to maximise this, which matters most when you're working under a fixed obstruction — a low doorway, a shipping container roof, or a low ceiling beam — where you need to lift a load without the mast itself growing taller. Without enough free lift, the forklift might lift the load fine in open space but be unable to do the same job under a height restriction.

What is side-shift?

Side-shift lets the operator move the forks left and right without repositioning the whole forklift. It's useful for fine-tuning where a pallet lands, especially in narrow aisles where there isn't room to keep pulling forward and reversing to adjust position. Most of our forklifts include this as standard.

What does fork length mean, and does it matter?

Fork length is simply how long the two forks are, front to back. It needs to suit the pallets you're using — forks that are too short won't fully support a deep pallet, and the load can become unstable. As a rule, the forks should reach at least three-quarters of the way under the load.

What is tilt?

Tilt is the forward and backward angle of the mast and forks. Tilting back slightly while carrying a load helps keep it stable and stops it sliding forward off the forks during transport. Tilting forward is mainly used when picking up or setting down a load, to help the forks slide under or out smoothly.

What's the difference between lift speed and lowering speed?

Lift speed is how fast the forks travel upward under load; lowering speed is how fast they come back down. These are usually different figures on a spec sheet because lowering is partly controlled by gravity and partly by the hydraulics, while lifting relies entirely on the hydraulic system doing the work. Faster speeds mean quicker cycle times, which matters more if the forklift is in near-constant use through the day.

Power & Running Costs

What's the difference between an electric, LPG, and diesel forklift?

Electric forklifts run on a rechargeable battery and produce no exhaust emissions, making them suitable for indoor use. LPG and diesel forklifts burn fuel and produce exhaust fumes, which generally restricts them to outdoor or well-ventilated environments unless fitted with additional filtration. Electric models also tend to be quieter and cheaper to run day to day, though they depend on having somewhere suitable to charge.

What type of battery does an electric forklift use, and does it matter?

Most electric forklifts use either lead-acid or lithium batteries. Lead-acid batteries are the traditional choice, cost less upfront, but need regular topping up with water and a dedicated charging area with ventilation. Lithium batteries cost more initially but charge faster, need no maintenance, and can be safely charged in normal working areas without special ventilation.

How long does an electric forklift take to charge?

This depends on the battery type and charger, but most forklifts in our range fully charge overnight from a standard socket. Lithium batteries can also be partially "top-up" charged during breaks in the working day, since they don't need a full charge cycle to stay healthy the way some lead-acid batteries do.

Does my electric forklift need three-phase power?

Not necessarily. Some electric forklifts require three-phase power for charging, which means an electrician needs to install a dedicated supply before the forklift can be used. Others, including our Mini and PF ranges, charge from a standard single-phase 13A socket — the same type used for normal appliances — so no extra electrical work is needed.

What is gradeability?

Gradeability is the steepest slope a forklift can climb (and safely hold) while carrying its rated load, usually expressed as a percentage. It mostly matters if you have ramps, loading bay slopes, or uneven yard surfaces to deal with. For flat, level indoor warehouse floors, it's rarely a deciding factor.

What is service weight?

Service weight is the total weight of the forklift itself, including the battery, but without any load on the forks. It matters for two practical reasons: it tells you whether your floor can take the weight (relevant for upper floors or older buildings), and it affects how the forklift is transported and delivered.

Safety & Compliance

What is LOLER, and what does "LOLER certified" mean?

LOLER (Lifting Operations and Lifting Equipment Regulations) is the UK law covering lifting equipment, including forklifts. It requires that lifting equipment is strong and stable enough for its intended use, and that it undergoes a "thorough examination" — a formal safety inspection — at regular intervals, typically every 12 months. When we say a forklift is LOLER certified, we mean it meets these requirements and is supplied ready for its first thorough examination cycle. It's a legal requirement for businesses using lifting equipment, not an optional extra.

What is anti-roll, and what is curve control?

Anti-roll is a stability feature that limits how much a forklift leans or tips when cornering, particularly when carrying a raised load. Curve control automatically reduces the forklift's speed when it detects the operator turning the steering wheel quickly, preventing sharp, unstable turns. Both features work in the background to reduce the risk of tipping, without the operator needing to do anything differently.

What is the blue safety light for?

The blue safety light projects a spot of light onto the floor a short distance in front of or behind the forklift. It's there to warn pedestrians and other operators that a forklift is approaching from around a corner or blind spot, before the forklift itself comes into view. It's especially useful in warehouses with narrow aisles or limited visibility at junctions.

What does CE marking mean?

CE marking shows that a product meets UK and EU safety, health, and environmental requirements for that type of equipment. For forklifts, this covers things like structural safety and electrical safety. It's not a measure of quality or performance — it's a baseline legal requirement — so a CE mark confirms the forklift is legal to use, not that it's necessarily the best one for your needs.