Hydraulic Jack

A hydraulic jack multiplies hand or air power through fluid pressure to lift vehicles, equipment, and structural loads. Bottle, floor, and toe patterns cover most lifting geometries on site.

Models

Varies by model

Rated capacity

Brands

How it works

Pumping the handle forces fluid from a reservoir through a check valve under a ram piston, and each small pump stroke lifts the large ram a little with multiplied force. A release valve bleeds fluid back to lower the load in a controlled way. Because fluid can leak and valves can creep, a jack lifts loads but never sustains them: stands do that.

Types & variants

Bottle jacks: Compact vertical rams with high capacity per pound of tool.
Floor jacks: Rolling trolley jacks with a low saddle and long lift arc.
Toe jacks: Low-entry claws that lift machinery from near floor level.
Air-over-hydraulic jacks: Shop-air assisted pumping for repeated heavy lifts.

Key specifications

Specification	Typical range	What it means
Rated capacity	Varies by model	The governing figure; recorded ranges for this class are corrupted and per-model plates rule.
Minimum height	Varies by model	Determines whether the saddle fits under the load's lift point.
Lift range	Varies by model	Total travel from collapsed to fully extended.

How the industry sizes it

Jacks are chosen by capacity with margin, collapsed height against the lift point, and travel to reach working height. Capacity figures in this class's grounding are unitless and unreliable; the rating plate on each jack governs.

Applications

Lifting vehicles and equipment for service
Positioning machinery and structural members
Raising loads onto cribbing and stands
Leveling and shoring adjustments during moves

Safety & operation

Loads are never worked under while supported only by a jack; rated stands or cribbing take the load first.
Jacks bear on firm, level ground with the saddle centered under a rated lift point.
A jack that drifts down under load has internal leakage and is retired for service.

Standards & certifications

ASME · PALD: Portable automotive lifting device standard covering jacks and stands.
ASME · B30.1: Jacks, industrial rollers, air casters, and hydraulic gantries.