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ASME PALD 13a-1989 — Swing Type Mobile Lifts Safety Standard Addenda (a)
🚗 ASME/ANSI PALD-13a-1989 is the first addenda to the Swing Type Mobile Lifts volume, ASME/ANSI PALD-13-1988. Approved by ANSI on July 19, 1989 and issued on September 15, 1989, it revises the affected pages of the 1988 edition through the replacement-page mechanism, with margin notes (a) marking the modified areas. The core of this revision is harmonizing the proof load requirement with load limiting devices: the definition of proof load and clause 3.4 now set a tiered verification multiplier — 150% for lifts without internal load limiting devices and 125% for lifts so equipped — while the operating controls clause is further clarified.
💡 Swing type mobile lifts use compressed air as the force-transmitting medium; their safety hinges on staying stable on loss of pressure, not bouncing on sudden unloading, and not failing under overload. This addenda refines the 1988 edition precisely around these points.
1. Principal Changes in This Addenda 📝
Per the Summary of Changes, the modifications in PALD-13a-1989 are:
| Page | Location | Change |
|---|---|---|
| 1 | Introduction | Second paragraph of General revised |
| 2 | Section I (Scope) | Revised |
| 5 | Section 2 — Definitions | Definition of proof load revised |
| 5 | 3.1 Operating Controls | Revised |
| 6 | 3.4 Proof Load | Revised |
⚠️ Addenda are issued as replacement pages; retain the addenda title and copyright pages and all replaced pages, and identify the modified areas by margin note (a). Later addenda build on this layer.
2. Proof Load and Load Limiting Devices 🔧
The most notable change is the tiered proof load requirement in 3.4, which answers the establishment of the term “load limiting device” in the definitions. Under the revised clause:
- Lifts without internal load limiting devices: must perform the proof load test of para. 5.1.1 with a proof load of 150% of rated capacity.
- Lifts equipped with internal load limiting devices: must perform the proof load test of para. 5.1.1 with a proof load of 125% of rated capacity.
The logic of the tiering: an internal load limiting device inherently caps the lift’s actual lifting capability, so a 150% physical overload is not attainable; 125% is the reasonable structural verification multiplier. Lifts without such a device must retain the 150% safety margin. Designers and inspectors must apply the verification multiplier that matches the equipment configuration.
| Configuration | Proof Load Multiplier | Basis | Purpose |
|---|---|---|---|
| No internal load limiting device | 150% of rated capacity | 3.4(a), 5.1.1 | Full-travel structural integrity verification |
| Internal load limiting device fitted | 125% of rated capacity | 3.4(b), 5.1.1 | Verify strength within the limiting device envelope |
🚨 The proof load tier must match the actual configuration: if a lift claims a limiting device that is not fitted, or the device’s set point does not match rated capacity, verification is inadequate and structural failure is possible under overload. Verify the device’s presence, set point, and sealing on acceptance.
3. Operating Controls and Other Requirements 🔩
The revised 3.1 requires controls designed so their operation is clear to the operator by position, function, labeling, or a combination thereof, and the release system must require intentional positive action to prevent accidental lowering. Together with the 1988 base requirements, the complete safety design of a swing type mobile lift includes travel limits (3.2), overload capacity (3.3), proof load (3.4), a secondary load holding means (3.5, automatic stop on loss of air pressure), and saddle restraints (3.6). For marking, rated capacity must be durably displayed in a prominent location, with manufacturer identification and a serial number or date code.
4. Engineering Practice Essentials 🛠️
- 🔍 Acceptance verification: confirm whether the lift has an internal load limiting device, check test reports against the applicable multiplier, and inspect the device’s set point and seal.
- 🔧 Operating discipline: keep loads evenly distributed on the saddles in the vehicle manufacturer’s specified areas; transfer the vehicle to proper supports immediately after lifting and never leave it supported by the lift.
- 📊 Testing scheduling: any design or design change affecting safety requires new sample proof tests, with no functional damage afterward.
- 📋 Version management: bind the 1988 edition with this addenda (a) replacement pages; continue stacking later addenda to form a complete revision chain.
💡 This addenda became effective 3 months after issuance, with prospective application only. Equipment already in production should be checked against the latest consolidated text during acceptance and periodic inspection.
From an engineering-application standpoint, this revision also links the limiting device to the test program: when a lift has an internal load limiting device, the device’s set point defines the boundary condition of verification, so inspectors should confirm the device is intact and functional before testing — a failed device must not be used to claim the lower 125% tier. Similarly, lifts without a limiting device should not evade the 150% verification by adding temporary flow-restricting elements. For users, the limiting device should be part of periodic inspection: check whether the set point has been altered, whether seals are intact, and record the results. Because this addenda also revises the operating controls clause, operator training should be updated to emphasize control identification and the intentional nature of release action, preventing accidental lowering through inadvertent release. In procurement, specify in the technical agreement whether the lift is configured with a limiting device and the corresponding proof load tier, and require verification test reports at the applicable multiplier on delivery.
5. Frequently Asked Questions ❓
❓ Q: Why two proof load tiers, 150% and 125%?
A: Lifts without internal load limiting devices rely on the structure itself for overload margin and must be verified at 150%; lifts with such devices have their capability capped, so 125% covers the limit state — safe and physically implementable.
A: Lifts without internal load limiting devices rely on the structure itself for overload margin and must be verified at 150%; lifts with such devices have their capability capped, so 125% covers the limit state — safe and physically implementable.
❓ Q: Are a “load limiting device” and a “secondary load holding means” the same?
A: No. A load limiting device caps lifting capacity; a secondary load holding means prevents unrestricted lowering on loss of air pressure. Different functions, different clauses.
A: No. A load limiting device caps lifting capacity; a secondary load holding means prevents unrestricted lowering on loss of air pressure. Different functions, different clauses.
❓ Q: What is the core change in operating controls?
A: The revised clause makes it explicit that control functions must be clear to the operator by position, function, labeling, or combination, and release requires intentional positive action — reinforcing the “no accidental lowering” principle.
A: The revised clause makes it explicit that control functions must be clear to the operator by position, function, labeling, or combination, and release requires intentional positive action — reinforcing the “no accidental lowering” principle.
🔍 Q: How do I confirm my copy of PALD-13 includes this addenda?
A: Check for margin note (a) and the page/location entries in the Summary of Changes; the most reliable route is to request current revision status and the latest consolidated text from the issuing body.
A: Check for margin note (a) and the page/location entries in the Summary of Changes; the most reliable route is to request current revision status and the latest consolidated text from the issuing body.
