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SAE J1356-2022: Minimum Performance Criteria for Falling Object Guards for Excavators
SAE J1356-2022 is a recommended practice that defines consistent test procedures and performance requirements for falling object protective structures (FOPS) on excavators. The standard applies to excavators working above ground near banks, mine faces, or in demolition where objects may fall onto the cab. It specifically covers top guards for protection from falling objects and front guards for protection from objects approaching the front of the cab.
Test Procedures and Performance Requirements
The standard specifies two primary laboratory tests: a drop test for the top guard and a penetration test for the front guard. In both cases, the guard must prevent any intrusion into the Deflection Limiting Volume (DLV) as defined in SAE J397.
🛠️ Engineer’s Note: All non-structural components such as removable panels, windows, or fittings that contribute to guard strength must be removed during testing. Only the guard structure itself is evaluated.
| Test | Test Object | Key Details |
|---|---|---|
| Top Guard Drop Test | 226.8 kg (500 lb) steel object, shaped as per Figure 1 | Drop height 5.2 m (17 ft). Small end must land within the vertical projection of the DLV. If the head area is not covered, multiple drop tests may be required. |
| Front Guard Penetration Test | Tapered end of the same object, pushed into the guard | Object is pushed into the front guard while force and deflection are measured. The small end must stay within the horizontal projection of the DLV. |
Deflection Limiting Volume (DLV) and Acceptance Criteria
The DLV is a volume that represents the operator’s space when seated. No part of the guard or test object may enter this volume during the test. The DLV is fastened to the same part of the machine as the operator seat. Grease or instrumentation can indicate contact.
Engineering Design Insight: The guard must be stiff enough to resist deformation under the specified impact or penetration load. Designers should pay attention to the projection of the DLV onto the guard surface and avoid placing major structural members in a way that leaves large unsupported areas. Thinner cover sections may require reinforcement to pass the test.
⚠️ Critical: If the drop location does not include at least a portion of the vertical projection of the head area, a second drop test is required. Always verify that the small end of the test object is placed within the DLV projection to ensure a valid laboratory evaluation.
Frequently Asked Questions
What is the required drop test mass for the top guard?
The drop test object must have a mass of not less than 226.8 kg (500 lb).
When are multiple drop tests required?
Multiple drop tests are required if the initial drop location does not cover the head area of the DLV, or if the top guard uses different materials or thicknesses in different areas above the DLV—each distinct area must then be tested separately.
How is the DLV positioned relative to the guard?
The DLV is fixed to the same part of the machine as the operator seat and oriented upright. The small end of the test object must be placed entirely within the vertical (top guard) or horizontal (front guard) projection of the DLV onto the guard surface.
What is the acceptance criterion for the front guard penetration test?
The front guard must prevent the penetration test object from entering the DLV while the object is pushed inward. Force and deflection are monitored, and contact with the DLV (or intrusion) indicates failure.
