How a Counterbalance Forklift Works
The name says it all. A counterbalance forklift lifts loads on forks at the front and relies on a heavy cast-iron or steel counterweight bolted to the rear frame to prevent the machine from tipping forward. The front axle acts as the pivot point — the load creates a tipping moment in one direction, and the counterweight creates an equal and opposite moment in the other.
This self-balancing design is what makes the counterbalance forklift so versatile. It needs no outriggers, no extended base, and no special floor preparation — just a reasonably flat, load-bearing surface. That simplicity is why you find counterbalance forklifts in virtually every warehouse, logistics hub, and construction yard in Singapore.
The counterbalance principle: balanced moments around the front axle keep the forklift stable. Load weight × load distance = Counterweight × counterweight distance.
The Stability Triangle
Every counterbalance forklift has three contact points with the ground: the two front wheels (fixed axle) and the rear axle, which pivots at a central point. These three points form a triangle — and the forklift remains stable only as long as the combined centre of gravity of the machine and its load stays inside this triangle.
Why this matters in practice
Overloading, lifting a load too high, cornering too fast, or operating on a slope can all shift the combined centre of gravity outside the stability triangle. This is why operators must always travel with the mast tilted back and forks at the lowest safe travel height — it keeps the centre of gravity low and well within the triangle.
Rated Capacity and Load Centre Distance
The capacity figure on a forklift's data plate — say, 3,000 kg — is always quoted at a standard load centre distance of 500 mm. The load centre is the horizontal distance from the face of the forks to the centre of gravity of the load. For a standard wooden pallet, this is typically around 500 mm. But for longer loads, heavy items positioned towards the outer end of the forks, or oversized pallets, the effective load centre can be significantly greater.
When the actual load centre exceeds 500 mm, the safe rated capacity must be reduced. The forklift's load chart specifies exactly how much capacity is available at different load centre distances. Ignoring this when handling non-standard loads is one of the most common causes of tip-overs on Singapore worksites.
As the load centre distance increases beyond 500 mm, the rated capacity decreases. Always check the forklift's load chart for non-standard loads.
Key Components of a Counterbalance Forklift
1Mast Assembly
The mast is the vertical steel structure at the front through which the carriage and forks travel. It telescopes upward via hydraulic cylinders. A duplex (two-stage) mast is standard for moderate lift heights in open facilities. A triplex (three-stage) mast achieves greater lift height for a given collapsed height — the right choice for high-bay warehouses or facilities with low overhead clearance, such as container loading. All masts can tilt forward (to engage and deposit loads) and backward (to secure the load during travel).
2Hydraulic System
The hydraulic system drives mast lift, mast tilt, sideshift (if fitted), and any auxiliary attachments. It comprises a pump, reservoir, control valves, hoses, and cylinders. Hydraulic integrity is critical — a failure causing uncontrolled mast descent under load is one of the most serious failure modes on any forklift. Regular hydraulic fluid checks and hose inspections are non-negotiable maintenance items.
3Drive and Steering
Counterbalance forklifts drive through the front axle and steer through the rear axle — the opposite of a car. This rear-wheel steering means the back of the machine swings outward during turns, creating a wider swing arc than most operators expect. New operators must internalise this behaviour before working near racking, columns, or pedestrians. The turning radius is a key specification when matching a forklift to a facility's aisle width.
4Counterweight
The counterweight is a solid block of cast iron or ballasted steel permanently fixed to the rear frame. Its mass is precisely calculated by the manufacturer to balance the rated load at the standard 500 mm load centre. It cannot and must not be modified in the field — adding weight to increase rated capacity invalidates the machine's certification and creates serious structural risk. If you need more capacity, rent a larger machine.
Fuel Types: Diesel, Electric, LPG & Petrol
The fuel type is one of the most consequential decisions when specifying a counterbalance forklift. It determines where the machine can legally and safely operate, how much it costs to run, and how it performs under load. Here is how the four options compare in the Singapore context.
Electric Forklift
Max capacity: Up to 5TBest for
Indoor warehouses, food-grade, cold storage, pharmaceutical
Diesel Forklift
Max capacity: Up to 23TBest for
Construction sites, outdoor yards, ports, heavy industrial
LPG Forklift
Max capacity: Up to 8TBest for
Mixed indoor-outdoor, multi-shift operations
Petrol Forklift
Max capacity: Up to 3TBest for
Light-duty, remote sites without LPG/electric infrastructure
RS Machinery rents diesel counterbalance forklifts from 1.5T to 23T and electric counterbalance forklifts from 1.5T to 5T in Singapore. All units are LM certified for construction site use.
View Fleet →How to Choose the Right Counterbalance Forklift
Matching the forklift to the job is not just about picking the right capacity. Five factors determine whether a machine will be a productive asset or a daily frustration on your site.
Capacity at the Actual Load Centre
Start with the heaviest load you will ever lift and its load centre distance. Do not use the headline capacity figure — check the load chart at your actual load centre. If your loads are consistently oversized or offset, you may need a machine with a higher headline capacity than you initially assumed.
Lift Height and Mast Configuration
Identify the maximum height loads must reach — typically the top rack beam plus 150–200 mm clearance. Then check the overhead clearance in your facility, particularly at doorways, mezzanine edges, and loading bay entrances. A triplex mast is usually the right choice for any high-bay warehouse or container operation.
Operating Environment
Indoor smooth concrete → electric with cushion tyres. Mixed indoor-outdoor paved surfaces → electric or LPG with pneumatic tyres. Outdoor heavy use, construction sites, yards → diesel with pneumatic tyres. Rough unpaved terrain → diesel with high ground clearance. Getting this wrong means either a machine that cannot legally operate in your space or one that underperforms on the surface.
Aisle Width and Turning Radius
Measure your narrowest aisle before specifying a machine. The forklift's turning radius at full steer lock must allow it to complete a 90° turn into the aisle in a single movement. A machine that requires a three-point turn in every aisle will cost you more in lost productivity than any rental rate saving.
Attachments
If you need a sideshifter, fork positioner, clamp, or rotator, specify it upfront. Attachments add weight to the front of the machine, which reduces the effective rated capacity. A 3,000 kg machine with a sideshifter fitted may only be rated at 2,700 kg — a reduction that must be accounted for in your specification.