ASME PALD 4-1987 — Vehicle Support Stands Safety Standard

28 10 月, 2026
ASME Standards

🛞 ASME/ANSI PALD-4-1987 is the “Vehicle Support Stands” volume of the ASME Safety Standard for Portable Automotive Lifting Devices. The PALD series has been developed since 1980 by the ASME Committee on Portable Automotive Lifting Devices, with each volume independently covering the design, marking, testing, operation, inspection, and maintenance of one equipment type. PALD-4 applies to vehicle support stands — devices that support a vehicle at fixed heights for maintenance or storage but lack the means of raising and lowering the vehicle. Stands are normally used together with jacks and function as the “second line of defense.”

💡 The value of a support stand lies in redundant safety: the lifting device raises and lowers the vehicle, while the stand carries the load afterward. Every requirement in PALD-4 serves one goal — the stand must never allow the vehicle to drop, tip, or slip under any expected condition.

1. Scope and Classification 📌

Section 1 states that this volume applies to stands used to support types of vehicles, as recommended by the manufacturer, at predetermined heights for the purpose of maintenance or storage. It does not include auxiliary stands used as supports for vehicle components or other special usage. The classification is the vehicle support stand with or without an adjustable column: for a fixed-height stand the entire stand except the saddle is considered the base; an adjustable stand varies its overall height by extending or retracting the column.

⚠️ Scope boundary: PALD-4 covers only stands that support a complete vehicle. Stands used to support components such as engines or transmissions belong in other volumes (e.g., PALD-15, Auxiliary Support Stands). Using a stand outside its scope invites unclear safety responsibility.

2. Design Requirements 🔧

Section 3 is the core of the Standard, imposing requirements on six aspects: base, column, locking device, operating controls, saddle, and stability.

Part / Requirement	Design Requirement	Safety Point
Base	Any configuration providing the equivalent of three or more points of contact with the ground; a circular, triangular, or polygonal shape (in plan view) is acceptable	The upper portion houses and guides the column, or supports the saddle on fixed-height stands
Column	Means shall be provided to prevent inadvertent separation of the column from the base; in the lowest operating position the lower end of the column shall not extend below the plane of the legs’ ground contact	Prevents pull-out and ground scraping at low positions
Locking device	Shall prevent adjustment of column height after the load has been applied; if a locking pin is used, it must be secured to the stand to prevent loss	Reliability of the pin- or pawl-type lock is decisive for safety
Operating controls	Readily visible and accessible; no pinch points, sharp edges, or snagging hazards; operation clear by position, function, labeling, or combination	Prevents misoperation and personal injury
Saddle	Configuration shall aid in properly positioning, supporting, and retaining the load	The saddle contacts the vehicle; anti-slip and alignment are key
Stability	Minimum horizontal distance from the edge of the saddle to the nearest edge of the projected base area shall be at least 8% of the maximum extended vertical height (H ≥ 8%V, measured with the column moved by hand to remove slack)	Quantified anti-tipping criterion

🚨 Stability is the lifeline of a support stand. The “8% rule” means the lower the stand and the wider the base, the safer it is. When selecting or fabricating a stand, always verify that the horizontal distance from the saddle edge to the base edge meets H ≥ 8%V at maximum extension; otherwise the stand can tip under off-center or external loads.

3. Proof Load and Design Qualification Testing 📋

Section 5 requires that every design, or design change affecting the stand’s safety, be subjected to a centered load test and an off-center load test. The proof load test applies, centrally to the saddle, a load of 150% of rated capacity to confirm structural integrity. After testing the stand must show no functional damage — no detrimental permanent deformation of the structure, saddle, or column that causes loss of load or failure to meet the design qualification limits. The off-center test simulates loads not perfectly centered and verifies stability under asymmetric loading.

💡 About the 150% proof load: rated capacity is the maximum load permitted in normal use; the proof load is a test load 50% above it, applied only to demonstrate design margin. It does not authorize continuous overload in service.

4. Product Marking and Warnings 🏷️

Section 4 requires every stand to carry:

Capacity marking: rated capacity marked prominently on the base by casting imprint, metal stamp, or durable materials and attaching methods.
Identification: identifying mark(s) of the original manufacturer or supplier; the manufacturer should be able to identify the date of manufacture of each stand.
Warning label: affixed with durable materials in a location readily visible to the operator, containing the word WARNING as a heading, a statement of the hazard, what to do to avoid or reduce the hazard, and a statement warning the operator to study, understand, and follow all instructions.

A typical warning given in the Standard reads: “WARNING: DO NOT OVERLOAD STAND. PLACE LOAD ON CENTER OF SADDLE ONLY. USE STANDS IN PAIRS, ON HARD LEVEL SURFACE.”

5. Engineering Practice 📌

🔍 Use stands in pairs: the sample warning explicitly requires pairs — one end of the vehicle must be carried by the stand while the other end is supported by an equivalent support; never support a whole vehicle on a single stand.
🔧 Hard, level surface: stands must sit on hard, level ground; soft, sloped, or oily surfaces compromise base-to-ground contact and invalidate the stability criterion.
📐 Center the load: the load must rest on the center of the saddle; off-center loading multiplies the tipping moment and erodes the design stability margin.
📋 Periodic inspection: before each use, check that the column locks reliably and that there is no base deformation or saddle damage; remove from service any stand showing functional damage (permanent deformation).
📊 Government adoption: where this Standard is adopted for governmental use, references to other national standards in the volume may be replaced by corresponding governmental regulations.

6. Frequently Asked Questions ❓

❓ Q: What is the difference between a support stand and a jack?
A: A jack can raise and lower a vehicle; a support stand only holds a vehicle at a fixed height. The correct sequence is: raise with the jack, place and lock the stand, then release and remove the jack — the stand carries the load during prolonged work or storage.

❓ Q: How should the H ≥ 8%V stability rule be interpreted?
A: H is the horizontal distance from the saddle edge to the nearest edge of the projected base area, and V is the maximum extended vertical height. The rule requires H to be at least 8% of V — the higher the stand, the wider the base must be — to avoid tipping under reasonable off-center loads.

🔍 Q: Can rated capacity and proof load be used interchangeably?
A: No. Rated capacity is the operating limit; the 150% proof load is used only in design qualification testing to demonstrate structural margin. The user must never subject a stand to more than its rated capacity.

❓ Q: How do the later Addenda relate to PALD-4-1987?
A: The 1987 edition is issued with an automatic addenda subscription. PALD-4a-1988, 4b-1989, and 4c-1991 revise the base edition through replacement pages, effective three months after each Addenda issue date. Cite the Standard as including the applicable addenda.