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ASME PALD 2-1987 — Transmission Jacks Safety Standard
📦 ASME/ANSI PALD-2-1987 is the Transmission Jacks volume of the Portable Automotive Lifting Devices (PALD) safety standard series — a formal revision of the 1983 edition (ANSI/ASME PALD-2-1983). Approved by the ASME Committee on Portable Automotive Lifting Devices and ANSI on September 7, 1987, and issued on December 31, 1987, it carries an automatic addenda subscription service under which addenda revisions become effective 3 months after each addenda issue date. Transmission jacks are used to remove and install transmissions and differential assemblies from automobiles and trucks — the dedicated lifting devices for the heaviest, most awkwardly shaped components in drivetrain service.
💡 A transmission assembly is heavy and has an offset center of gravity and an irregular contour. A purpose-built transmission jack matches its adjustable platform and brackets to the component contour and provides vertical lift plus tilt adjustment for precise alignment — capabilities no ordinary jack offers.
1. Scope and Classifications 📌
This volume classifies equipment by the force-transmitting means, with Figures 1 through 5 showing typical products:
| Classification | Force-Transmitting Means | Typical Type (Figure) | Construction Features |
|---|---|---|---|
| Pneumatic/Hydraulic | Compressed air driving a hydraulic pump | Pneumatic/hydraulic transmission jack (Fig. 1) | Air-driven hydraulic pump reduces manual effort |
| Hydraulic | Relatively incompressible fluid (e.g., oil) | Tall and low hydraulic transmission jacks (Figs. 2, 4) | Hydraulic cylinder lift with tilt adjustment |
| Mechanical | Mechanical lifting means and threads | Tall and low mechanical transmission jacks (Figs. 3, 5) | Gears, screws, and ratchet mechanisms |
Where a combination of these force-transmitting means is used, the Standard requires each system to be tested to conform to this volume. The Standard covers the design, construction, marking, operation, maintenance, and inspection of the equipment, but does not apply to similar lifting devices for other commercial or industrial use, such as those within the scope of ASME/ANSI B30.1, Jacks.
2. Design and Safety Technical Requirements 🔧
Design (Section 3) is the heart of this Standard, addressing the special loading conditions of dedicated lifting equipment:
- Lift platform assembly: the portion of the jack that contacts the transmission or differential assembly, including brackets, adapters, and load restraints supplied by the manufacturer; it must match the component contour and hold the load securely.
- Load restraint: a device supplied by the manufacturer to retain the load on the lift platform, preventing the transmission from sliding during raising, lowering, and movement.
- Internal load limiting device: a device that limits the lifting capacity of the jack to prevent structural overload (optional on some models).
- Stability: the platform must keep the load level through tilt adjustment, and the complete jack must not tip under rated and off-center loading.
- Operating controls: raise, lower, tilt, and travel must be easy to control and reliably lockable in any position.
🚨 The key safety factor of a transmission jack is load restraint: raising, lowering, or moving the jack with the transmission not securely fixed to the platform brackets and restraints is one of the most common — and most dangerous — causes of incidents in service work. Keep all body parts clear of the space beneath the transmission during any movement.
3. Marking and Design Qualification Testing 📋
Product marking and identification (Section 4) require clear marking of rated capacity and manufacturer identity to prevent overload misuse. Design qualification testing (Section 5) is the verification gate before a product reaches the market:
- Proof-load testing: the product must withstand the specified proof load without functional damage (permanent deformation causing loss of sealing capability, loss of load, or worse).
- Overload protection verification: jacks fitted with internal load limiting devices must be verified to act reliably above rated capacity.
- Stability testing: verify whole-unit stability under rated and specified off-center loading.
- Sealing performance: hydraulic and pneumatic systems must not leak at specified pressures.
⚠️ Design qualification testing applies to the model, not to each individual unit. Production units must be kept consistent with the qualified prototype through process quality control; any design change affecting load capacity or stability calls for re-qualification.
4. Operation, Maintenance, and Engineering Practice 🛠️
- 👷 Personnel qualification: operators must be trained and qualified, and must understand the component weight, center-of-gravity offset, and the relationship to the jack’s rated capacity.
- 🔧 Pre-use inspection: check bracket/adapter fit, restraint condition, hydraulic leaks, and the reliability of tilt and locking mechanisms.
- 📐 Work sequence: secure the transmission first → raise or lower slowly → fine-tune tilt during alignment → release bracket bolts only after the component is fixed — keep the load steady throughout.
- 🔍 Periodic inspection: hydraulic oil level and quality, seals, locking mechanisms, and wheel wear should be on the scheduled inspection list; take the unit out of service on any abnormality.
- 📋 Instructions and warnings: keep the manufacturer’s instructions (Section 6) and warnings at the worksite, covering floor conditions (hard and level) and levelness judgment.
✅ Sound practice: keep the transmission low — position and secure it close to the floor/chassis level, then raise slowly to working height. A low center of gravity dramatically reduces tip and drop risk.
5. Frequently Asked Questions ❓
❓ Q: How does a transmission jack differ from a common hydraulic jack?
A: A common jack only lifts vertically. A transmission jack combines lift with tilt adjustment and interchangeable platform brackets, is designed to carry the transmission/differential assembly and slide beneath it, and includes load restraints that ordinary jacks do not have.
A: A common jack only lifts vertically. A transmission jack combines lift with tilt adjustment and interchangeable platform brackets, is designed to carry the transmission/differential assembly and slide beneath it, and includes load restraints that ordinary jacks do not have.
🔍 Q: How do I choose among hydraulic, pneumatic, and mechanical types?
A: Hydraulic is most common — smooth and precise. Pneumatic/hydraulic suits high-frequency work and saves effort but needs an air supply. Mechanical types are simple, need no oil, and fit low-frequency, low-maintenance applications. Consider work frequency, air availability, and maintenance capability.
A: Hydraulic is most common — smooth and precise. Pneumatic/hydraulic suits high-frequency work and saves effort but needs an air supply. Mechanical types are simple, need no oil, and fit low-frequency, low-maintenance applications. Consider work frequency, air availability, and maintenance capability.
❓ Q: How should rated capacity be determined?
A: Base it on the maximum weight of the assembly to be lifted — including transfer cases, brackets, or other attached components — and leave margin. Never work “on the line” at rated capacity.
A: Base it on the maximum weight of the assembly to be lifted — including transfer cases, brackets, or other attached components — and leave margin. Never work “on the line” at rated capacity.
❓ Q: Can a transmission jack be used in a pit or under a vehicle hoist?
A: Yes, provided the floor is hard and level, the vehicle is reliably supported by the hoist or stands, the work area is free of oil and obstructions, and the vehicle-lifting equipment’s own safety requirements are observed.
A: Yes, provided the floor is hard and level, the vehicle is reliably supported by the hoist or stands, the work area is free of oil and obstructions, and the vehicle-lifting equipment’s own safety requirements are observed.
