- Part Number:1926
- Part Number Title:Safety and Health Regulations for Construction
- Subpart:1926 Subpart W
- Subpart Title:Rollover Protective Structures; Overhead Protection
- Standard Number:
- Title:Minimum performance criteria for rollover protective structures for designated scrapers, loaders, dozers, graders, and crawler tractors.
- GPO Source:
Table W-1 contains a listing of the required apparatus for all types of equipment described in paragraph (a) of this section.
TABLE W-1 ____________________________________________________________________ | Means to measure | Accuracy ____________________________________|_______________________________ | Deflection of ROPS, inches .........| + or - 5 percent of deflection | measured. Vehicle weight, pounds .............| + or - 5 percent of the weight | measured. Force applied to frame, pound ......| + or - 5 percent of force | measured. Dimensions of critical zone, inches.| + or - 0.5 in ____________________________________|_______________________________
Energy absorbing capabilities of ROPS shall be verified when loaded laterally by incrementally applying a distributed load to the longitudinal outside top member of the ROPS, as shown in Figure W-1, W-2, or W-3, as applicable. The distributed load must be applied so as to result in approximately uniform deflection of the ROPS. The load increments should correspond with approximately 0.5 in. ROPS deflection increment in the direction of the load application, measured at the ROPS top edge. Should the operator's seat be offcenter, the load shall be applied on the offcenter side. For each applied load increment, the total load (lb.) versus corresponding deflection (in.) shall be plotted, and the area under the load-deflection curve shall be calculated. This area is equal to the energy (in.-lb.) absorbed by the ROPS. For a typical load-deflection curve and calculation method, see Figure W-5.
FIGURE W-1 - Vertical loading setup for all types of equipment described in 1518.1001(a) (For Figure W-1, Click Here) FIGURE W-2 - Test setup for rubber-tired self-propelled scrapers. (For Figure W-2, Click Here) FIGURE W-3 - Test setup for rubber-tired front-end loaders, rubber-tired dozers, and motor graders. (For Figure W-3, Click Here) FIGURE W-4 - Sideloading setup for crawler tractors and crawler loaders. (For Figure W-4, Click Here)
Incremental loading shall be continued until the ROPS has absorbed the amount of energy and the minimum applied load specified under paragraph (f) of this section has been reached or surpassed.
The low temperature impact strength of the material used in the ROPS shall be verified by suitable material tests or material certification (see paragraph (f)(2)(iv) of this section).
FIGURE W-5 - Determination of energy area under force deflection curve for all types of ROPS equipment defined in 1926.1001 (For Figure W-5, Click Here)
The energy requirement for purposes of meeting the requirements of paragraph (e)(1) of this section is to be determined by referring to the plot of the energy versus weight of vehicle (see Figure W-6 for rubber-tired self-propelled scrapers; Figure W-7 for rubber-tired front-end loaders and rubber-tired dozers; Figure W-8 for crawler tractors and crawler-type loaders; and Figure W-9 for motor graders). For purposes of this section, force and weight are measured as pounds (lb.); energy (U) is measured as inch-pounds.
FIGURE W-6 - Energy absorbed versus vehicle weight. (For Figure W-6, Click Here)
The load magnitude for purposes of compliance with paragraph (e)(2) of this section is equal to the vehicle weight. The test of load magnitude shall only be made after the requirements of paragraph (f)(2)(i) of this section are met.
FIGURE W-7 - Energy absorbed versus vehicle weight. (For Figure W-7, Click Here)
Material used in the ROPS must have the capability of performing at zero degrees Fahrenheit, or exhibit Charpy V notch impact strength of 8 foot-pounds at minus 20 deg. Fahrenheit.
This is a standard Charpy specimen as described in American Society of Testing and Materials A 370, Methods and Definitions for Mechanical Testing of Steel Products (available at each Regional Office of the Occupational Safety and Health Administration). The purpose of this requirement is to reduce the tendency of brittle fracture associated with dynamic loading, low temperature operation, and stress raisers which cannot be entirely avoided on welded structures.
FIGURE W-8 - Energy absorbed versus vehicle weight. (For Figure W-8, Click Here) FIGURE W-9 - Energy absorbed versus vehicle weight. (For Figure W-9, Click Here)
Definitions. For purposes of this section, "vehicle weight" means the manufacturer's maximum weight of the prime mover for rubber-tired self-propelled scrapers. For other types of equipment to which this section applies, "vehicle weight" means the manufacturer's maximum recommended weight of the vehicle plus the heaviest attachment.
FIGURE W-10 - Minimum horizontal load factor for self-propelled scrapers. (For Figure W-10, Click Here) FIGURE W-11 - Minimum horizontal load for rubber-tired loaders and dozers. (For Figure W-11, Click Here) FIGURE W-12 - Minimum horizontal load factor for crawler tractors and crawler-type loaders. (For Figure W-12, Click Here) FIGURE W-13 - Minimum horizontal load factor for motor graders. (For Figure W-13, Click Here)