ton-force (Metric) to ton-force (Short/UK)

Match the jack to 1.5–2× the heaviest load you will lift. A passenger car weighs 1.2–2.0 tonnes, so a 3 tf bottle jack covers most cars with a safety margin. An SUV or light truck (2.5–3.5 tonnes) needs a 5–6 tf jack. Floor jacks for home garages are typically rated at 2–3 tf. Never work under a vehicle supported only by a jack — always use rated jack stands, because a jack can lose hydraulic pressure without warning.

Crane operators and riggers think in terms of the mass being lifted — "a 20-tonne load" is more intuitive than "a 196 kN load." Ton-force keeps the number identical to the mass in tonnes, which reduces cognitive load and rigging errors on job sites. Many crane load charts list both tf and kN, but the tonne figure is what gets communicated over radio.

Metric ton-force is based on 1,000 kg (9,806.65 N), short ton-force on 2,000 lb / 907.2 kg (8,896.4 N), and long ton-force on 2,240 lb / 1,016 kg (9,964.0 N). The metric and long ton-force are within 2% of each other, while the short ton-force is about 9% smaller. Mixing them up in crane or press specifications can cause dangerous overloads.

Small workshop presses operate at 10–50 tf, automotive stamping presses at 500–2,500 tf, and the largest forging presses exceed 50,000 tf (about 490 MN). Press manufacturers in Europe and Asia commonly rate capacity in metric tonnes-force, while US makers use short tons or kilonewtons depending on the market.

Yes. "Metric ton-force," "tonne-force," and the symbol "tf" all refer to the same unit: the gravitational force on 1,000 kg at standard gravity. The word "metric" is added to distinguish it from the US short ton-force and the UK long ton-force. In SI-aligned countries, "tonne-force" is the more common phrasing.

A long ton-force (UK) is based on 2,240 lb (≈ 9,964 N), while a short ton-force (US) is based on 2,000 lb (≈ 8,896 N). The long ton-force is about 12% larger. Confusing the two is a common source of error when interpreting crane ratings or press capacities from British versus American documentation.

The long ton (2,240 lb) was the standard UK weight unit before metrication, rooted in the medieval practice of measuring goods in multiples of 20 hundredweight (112 lb each). Legacy shipbuilding, mining, and heavy engineering documents still reference long tons. Modern British engineering has largely switched to metric tonnes, but older equipment and archived specs remain in long ton-force.

Multiply long ton-force by 9.96402 to get kilonewtons. So 10 long ton-force ≈ 99.6 kN. For a rough estimate, 1 long ton-force is very close to 10 kN — a convenient approximation for quick conversions when reviewing older British engineering documents.

Older British crane certifications, Royal Navy vessel displacement figures, and pre-1970s structural steel test reports commonly use long ton-force. Maritime salvage operations and heritage railway maintenance also reference long tons. When refurbishing Victorian-era bridges or machinery, engineers must convert these legacy ratings to modern SI units for compliance with current codes.

The Royal Navy measured displacement in long tons for centuries, and major warship classes are historically known by their long-ton figures — HMS Dreadnought at 18,120 long tons, HMS Hood at 46,680 long tons. Modern Royal Navy vessels are specified in metric tonnes, but naval history, treaty references (e.g., the Washington Naval Treaty's 35,000 long-ton capital ship limit), and ship recognition databases retain long-ton figures because changing them would break continuity with a vast body of historical documentation.