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ASME PALD 9-1987 — Upright Type Mobile Lifts Safety Standard
🏗️ ASME/ANSI PALD 9-1987 is Volume 9 of the ASME series Safety Standard for Portable Automotive Lifting Devices, dedicated to Upright Type Mobile Lifts. Approved by the American National Standards Institute (ANSI) on June 4, 1987, this volume sets requirements for the design, marking, qualification testing, operation, maintenance, and inspection of these devices. An upright type mobile lift is characterized by a pair of laterally spaced lifting members that raise and lower in unison, contacting the vehicle at two points across its axis of symmetry on the bumper, bumper supports, or frame members, for the purpose of raising the wheels of one end free of the ground — widely used for tire changing, brake service, and underbody maintenance.
💡 The “mobile” attribute makes upright type mobile lifts the workhorse of small repair shops and mobile service fleets: no permanent installation is required and the lift can be wheeled freely between work bays. The corresponding safety requirements focus on stability, synchronized lifting, and protection against uncontrolled lowering.
1. Overview and Scope 📌
This Standard applies to upright type mobile lifts driven by hydraulic, pneumatic, or mechanical means. It is organized into seven sections: Section 1 — Scope, Purpose, Classification, and Illustration; Section 2 — Definitions; Section 3 — Design (operating controls, travel limit, overload capacity, internal load limiting device, proof load, secondary load holding means, saddles); Section 4 — Product Marking and Identification; Section 5 — Design Qualification Testing; Section 6 — Product Instructions and Warnings; and Section 7 — Operation, Maintenance, and Inspection. Clause 1.3 classifies lifts into hydraulic (with or without internal load limiting constraints), pneumatic, and mechanical.
The Standard is limited to portable automotive lifting devices used during automotive service, maintenance, and storage; it does not apply to similar lifting devices built for other commercial or industrial use, such as those within the scope of ASME/ANSI B30.1, Jacks. As with other PALD volumes, it stresses that portable lifting devices carry hazards that cannot be precluded by mechanical means alone but only by trained, qualified, and careful operators.
⚠️ Unlike PALD 8’s frame jack, which lifts a single wheel, the PALD 9 upright type mobile lift raises one whole end of the vehicle through two-point contact spanning the vehicle’s axis of symmetry. The structures and operating logic differ completely — keep them distinct in selection and training.
2. Key Definitions 📖
Section 2 contains the terminology essential to the whole Standard:
- Lift: a vehicle lifting device that raises the wheels of one end of a vehicle free of the ground.
- Lifting member: the moving portion of a lift upon which the saddles are mounted.
- Saddle: the portion of the lift that contacts the vehicle.
- Base: the stationary portion of a lift to which the lifting members are attached.
- Rated capacity: the maximum published operating load the lift is designed to lift or move throughout its range of travel.
- Proof load: a load greater than the rated capacity, applied to the saddle(s) and transmitted to the structure, to verify the integrity of the structure.
- Overload: a load exceeding the rated capacity of the lift.
- Functional damage: any permanent deformation of the lift’s structure and/or loss of sealing capacity in its hydraulic and/or pneumatic components that renders the lift unable to meet the design qualification testing of this Standard.
3. Technical Requirements and Design Essentials 🔧
Section 3 — Design — is the technical heart of the Standard, imposing a systematic set of safety requirements.
| Design Requirement | Key Content | Safety Purpose |
|---|---|---|
| Operating controls (3.1) | Controls readily visible and accessible, free of pinch points, sharp edges, and snagging; release requires intentional positive action to prevent accidental lowering | Prevent misoperation and accidental descent |
| Travel limit (3.2) | Each lift provided with a positive means to prevent the load being raised beyond the design limit of travel | Prevent over-travel instability |
| Overload capacity (3.3) | All lifts designed to meet at least the minimum overload capacity of 3.5 | Maintain structural safety margin |
| Internal load limiting device (3.4) | Hydraulic lifts may be equipped with internal load limiting devices | Cap lifting capacity against overload |
| Proof load (3.5) | Lifts without internal load limiting devices: 150% of rated capacity; with devices: 125% | Verify structural integrity |
| Secondary load holding means (3.6) | A device prevents unrestricted lowering in the event of pressure loss | Prevent falling-load injuries |
| Saddles (3.7) | Raised protrusions (tang or rail) on the leading edge act as load restraint; outward lateral adjustment limited | Prevent vehicle slip-off |
✅ The two-tier proof load of 3.5 is a thoughtful design: on lifts with internal load limiting devices, the structure is never forced beyond a smaller multiple of rated capacity, so 125% proof is sufficient; lifts without the device must prove 150%, guaranteeing structural integrity even under the worst overload.
4. Marking, Testing, and Documentation 🏷️
Section 4 requires that rated capacity be marked in a prominent location by cast imprint, metal stamp, or durable materials; that the lift carry identification of the original manufacturer; that a serial number or date code be stamped; and that a warning be affixed durably where readily visible to the operator, containing the heading WARNING, a statement of the hazard, what to do to avoid or reduce it, and a statement to study, understand, and follow all instructions. Section 5 requires sample proof tests for each design or design change affecting safety, including proof load tests, travel limit tests, and, for pneumatic lifts, the instantaneous load loss test. Section 6 requires instructions and warnings; Section 7 requires a routine inspection and maintenance regime.
🚨 The most dangerous scenario for pneumatic lifts is instantaneous load loss: when the load suddenly vanishes (for example, the vehicle slips off the saddles), the lifting member accelerates uncontrolled. The test loads the lift to rated capacity, raises it to a height that maximizes momentum, and verifies restraint — in operation, no one may stand under the arms or in the load-release path.
5. Engineering Practice Essentials 🛠️
- 🔍 Selection: verify that rated capacity covers the serviced vehicles’ corresponding axle-end load; prefer models with internal load limiting devices and secondary load holding means.
- 📍 Positioning: place saddles strictly at the vehicle manufacturer’s specified bumper/frame points, keeping load equal on each saddle.
- 🧯 Surface: use only hard level surfaces capable of carrying the load; operating a mobile lift on slopes or soft ground severely degrades stability.
- 🔧 Inspection and maintenance: periodically check hydraulic sealing, air circuits, mechanical drives, and saddle restraint protrusions; take a leaking or deformed unit out of service immediately.
- 📋 Training: operators should master the seven requirement areas of the Standard and strictly avoid overload, off-center loading, and unauthorized work beneath the vehicle.
6. Frequently Asked Questions ❓
❓ Q: What is the difference between an upright type mobile lift and a fixed two-post lift?
A: The lift in this Standard is “mobile” — it can be moved without a load from one work area to another. A fixed two-post lift is a different class of shop equipment and generally falls outside this scope. Check whether the unit has wheels before classifying it.
A: The lift in this Standard is “mobile” — it can be moved without a load from one work area to another. A fixed two-post lift is a different class of shop equipment and generally falls outside this scope. Check whether the unit has wheels before classifying it.
❓ Q: Why are proof loads set at 150% and 125%?
A: Clause 3.5 states that lifts without internal load limiting devices must pass the proof load test at 150% of rated capacity, while those equipped with such devices need only 125%. Because the limiting device already caps the maximum load the structure can see, the proof requirement is relaxed accordingly; the device may be deactivated during the test.
A: Clause 3.5 states that lifts without internal load limiting devices must pass the proof load test at 150% of rated capacity, while those equipped with such devices need only 125%. Because the limiting device already caps the maximum load the structure can see, the proof requirement is relaxed accordingly; the device may be deactivated during the test.
❓ Q: Why does the Standard require a “secondary load holding means”?
A: If hydraulic or pneumatic pressure is lost, a loaded lift would descend out of control — one of the most lethal failure modes of this equipment. The secondary holding means (e.g., mechanical locking or redundant check valves) ensures that even with power loss, the load cannot free-fall.
A: If hydraulic or pneumatic pressure is lost, a loaded lift would descend out of control — one of the most lethal failure modes of this equipment. The secondary holding means (e.g., mechanical locking or redundant check valves) ensures that even with power loss, the load cannot free-fall.
🔍 Q: Does PALD 9 cover industrial scissors lifts?
A: No. Section II states the Standard does not apply to similar lifting devices designed for other commercial or industrial use (e.g., those within B30.1). Scissors type mobile lifts for automotive service are covered by the separate PALD-14 volume.
A: No. Section II states the Standard does not apply to similar lifting devices designed for other commercial or industrial use (e.g., those within B30.1). Scissors type mobile lifts for automotive service are covered by the separate PALD-14 volume.
