Oct. 16, 2026
Car jack specifications often place capacity, minimum height and maximum height in the same table. These figures describe different parts of a jack's operating envelope: the load it is rated to lift, the height at which its saddle begins, and the highest position its lifting mechanism can reach.
The terms apply across the bottle, floor and scissor jacks found in the Autools car jack range, although the mechanism behind each measurement differs by jack type.
| Specification term | What it normally describes |
| Rated capacity | The maximum load assigned to the jack by its manufacturer |
| Minimum height | The height from the base or floor to the load-contact point when fully lowered |
| Maximum height | The height from the base or floor to the load-contact point when fully raised |
| Lifting range | Either the minimum-to-maximum height interval or the difference between those two figures, depending on the data sheet |
| Stroke or hydraulic lift | The vertical travel produced by the ram or hydraulic lifting mechanism |
| Extension screw | A threaded mechanical adjustment on some bottle jacks that adds height separately from hydraulic travel |
These are general meanings, not substitutes for a model drawing. Measurement points can vary, so the individual specification table remains the controlling reference.
Rated capacity is the manufacturer's stated maximum load for the jack. It is commonly shown in tonnes, tons, kilograms or pounds. OSHA requires this rating to be legibly marked on a jack and not exceeded.
The word ton requires context. A metric tonne is 1,000 kilograms, while a US short ton is 2,000 pounds. They are not the same unit, so the unit label is part of the specification.
Capacity does not describe height. Two jacks can share a capacity rating while having different minimum heights, strokes and maximum heights.
Minimum height is the jack's lowest working height, normally measured from the supporting surface to the top of the saddle or other load-contact point when the jack is fully lowered. Product literature may also call it closed height, retracted height or pickup height.
The labels are not always perfectly interchangeable. Floor, bottle and scissor jack drawings reflect different structures, so the drawing shows exactly where the stated dimension begins and ends.
Maximum height or extended height is the highest specified position of the load-contact point. It is normally measured from the same reference surface used for minimum height.
This figure can combine more than one movement. On a bottle jack, for example, the published maximum may include hydraulic ram travel and the full usable extension screw. The component columns clarify what has been included.
Lifting range is one of the least consistent labels. Some catalogues present it as an interval, such as a minimum height followed by a maximum height. Others use it for the total vertical difference between those positions. When only one lifting-range number appears, its meaning depends on the accompanying drawing or formula.
Stroke, ram travel and hydraulic lift refer more specifically to movement produced by the lifting mechanism. In a hydraulic bottle jack, this is the distance travelled by the ram under hydraulic pressure. It does not automatically include a threaded extension screw.
For a simple specification layout, the relationship may be expressed as:
maximum height = minimum height + hydraulic lift + extension-screw adjustment
Hydraulic bottle-jack tables commonly separate these values. Small differences can appear because of rounding or different measurement points.
Many bottle jacks place a threaded extension between the ram and saddle. It changes the initial contact height before hydraulic travel begins and may be labelled extension screw, screw extension or adjustable height.
The extension is a mechanical adjustment, not extra hydraulic stroke. This distinction explains why a bottle jack can list minimum height, hydraulic lift, screw extension and maximum height as four separate columns. Some models omit the extension entirely, so the field cannot be assumed across a complete range.
A floor jack has a horizontal chassis and lifting arm, so its tables often emphasize minimum and maximum saddle height. A bottle jack has an upright body and ram, making separate stroke and extension-screw fields useful. A scissor jack uses a mechanical screw and crossed arms, so its closed and extended dimensions describe that mechanism rather than a hydraulic cylinder. The same term must therefore stay connected to its product type and model drawing.
Capacity establishes the load boundary, while height figures establish dimensional travel. Neither confirms a vehicle's lifting points, ground conditions or support arrangement.
A jack is a lifting device rather than permanent support for work beneath a raised load. OSHA states that a raised load must be cribbed, blocked or otherwise secured at once. Product instructions and vehicle-manufacturer information provide the model- and application-specific safety details.
Q: Is lifting range the same as maximum height?
A: Not necessarily. Maximum height is the highest stated position. Lifting range may mean the interval from minimum to maximum height or the amount of travel between them.
Q: Does maximum height always include the bottle jack extension screw?
A: Many specification tables include the fully extended screw in maximum height, but the model drawing and column definitions determine the answer for a particular jack.
Q: Are 'ton' and 'tonne' interchangeable in jack specifications?
A: No. A tonne is a metric unit equal to 1,000 kilograms. A US short ton equals 2,000 pounds, so the stated unit is part of the capacity specification.
Q: Is hydraulic lift the same as total lifting range?
A: Not always. Hydraulic lift describes travel created by the hydraulic mechanism. Total height change may also include an extension screw or another adjustment.
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