Definitions for powered tools

Under 1910.241(a)(1) a hammer-operated piston tool (low-velocity type) is a captive-piston explosive-actuated fastening tool that starts the fastener at rest in contact with the work surface and must not propel a stud, pin, or fastener with a mean velocity over 300 feet per second when measured 6.5 feet from the muzzle.

• Practical note: this means the tool is designed so that with any commercially available load that properly chambers in the tool the fastener’s measured mean velocity stays at or below 300 ft/s. See the definition at 1910.241(a)(1).

Under 1910.241(a)(2) a high-velocity tool is any tool or machine which, when used with a load, propels or discharges a stud, pin, or fastener at velocities in excess of 300 feet per second (measured 6.5 feet from the muzzle) for the purpose of affixing, impinging upon, or penetrating another object or material.

• In practice: if a tool can send a fastener faster than 300 ft/s under the test condition in the definition, it meets OSHA’s high‑velocity definition. See 1910.241(a)(2).

Under 1910.241(a)(3) a low-velocity piston tool is a tool that uses a captive piston to drive a stud, pin, or fastener into a work surface and is designed so that, with any commercially available load that properly chambers, it will not cause the fastener to have a mean velocity in excess of 300 feet per second when measured 6.5 feet from the muzzle.

• Difference: the emphasis is on a captive piston design and meeting the 300 ft/s velocity limit; see 1910.241(a)(3).

Under 1910.241(a)(4) a "stud, pin, or fastener" means a fastening device specifically designed and manufactured for use in explosive-actuated fastening tools.

• Practical implication: only use fasteners specifically made for the tool model in question; incompatible or makeshift fasteners are not covered by the design assumptions in the definition. See 1910.241(a)(4).

Under 1910.241(a)(5) "to chamber" means to fit properly without the use of excess force, with the case being duly supported.

• In plain terms: a load "chambers" when it slides into position in the tool easily and seats correctly (no forcing or bending). See 1910.241(a)(5).

Under 1910.241(a)(6) an explosive powerload, or "load," is any substance in any form capable of producing a propellant force.

• Practical implication: cartridges, charges, or similar energetic charges used to fire explosive-actuated tools are considered "loads" under this definition. See 1910.241(a)(6).

Under 1910.241(a)(7) the word "tool" refers to an explosive-actuated fastening tool (unless otherwise indicated) and includes all accessories pertaining to that tool.

• Practical point: when the subpart says "tool," it covers the device and relevant accessories (e.g., shields, chucks) unless the language specifies otherwise. See 1910.241(a)(7).

Under 1910.241(a)(8) a "protective shield or guard" is a device or guard attached to the muzzle end of the tool designed to confine flying particles.

• Use this type of shield to reduce the chance of fragments or fastener pieces ejecting toward the operator or bystanders. See 1910.241(a)(8).

Under 1910.241(b)(1) "mounted wheels" are small abrasive wheels (usually 2 inches diameter or smaller) of various shapes, bonded organically or inorganically, secured to plain or threaded steel mandrels.

• Practical use: these are the small grinding or cutting wheels used in hand-held tools like die grinders; see 1910.241(b)(1).

Under 1910.241(b)(3) tuck pointing wheels are usually Type 1, reinforced organic bonded wheels used for grinding out cement, mortar, or other nonmetallic jointing materials, and OSHA limits tuck pointing wheels to reinforced organic bonded types.

• Additional note: OSHA points to the requirements in 1910.243(c)(1)(ii)(c) when using tuck pointing wheels; see 1910.241(b)(3).

Under 1910.241(b)(4) "portable grinding" means a grinding operation performed with a grinding machine that is designed to be hand-held and easily moved from one location to another.

• Practical reminder: portable grinders must be handled and guarded appropriately for their portable nature; see 1910.241(b)(4).

Under 1910.241(b)(5) organic bonded wheels are abrasive wheels bonded by an organic material such as resin, rubber, shellac, or a similar bonding agent.

• In short: these are non-metallic-bond wheels where the bonding agent is an organic compound; see 1910.241(b)(5).

Under 1910.241(b)(6) a safety guard is an enclosure designed to restrain pieces of a grinding wheel and provide protection if the wheel breaks during operation.

• Why it matters: the guard helps contain fragments and reduces risk of injury from wheel failure; employers should ensure guards are in place and appropriate for the wheel being used. See 1910.241(b)(6).

Under 1910.241(b)(7) "reinforced wheels" are a class of organic wheels that contain strengthening fabric or filament; the term does not include wheels that use mechanical additions like steel rings, steel cup backs, wire, or tape winding.

• Practical guidance: when a standard or equipment calls for "reinforced" wheels, use wheels with internal reinforcement (fabric/filament), not ones made stronger by external metal parts. See 1910.241(b)(7).

Under 1910.241(b)(8) Type 11 flaring cup wheels are side grinding wheels with a flared or tapered wall outward from the back (wall thickness at the back normally greater than at the grinding face) and are subject to the same use and mounting limitations as Type 6 straight cup wheels, including a minimum back thickness of at least one-fourth the wheel thickness (E ≥ 1/4 T).

• Make sure unthreaded-hole Type 11 wheels have an inside flat dimension large enough to accommodate a suitable flange. See 1910.241(b)(8).

Under 1910.241(b)(9) Type 6 straight cup wheels have specific dimensions for diameter, thickness, hole size, rim thickness, and back thickness; grinding is always performed on the rim face (W dimension).

• Practical point: use these wheels with the grinding action on the rim face only and follow the dimensional and mounting limitations in the definition. See 1910.241(b)(9).

Under 1910.241(b)(10) Type 1 straight wheels are peripheral grinding wheels with diameter, thickness, and hole dimensions and must be mounted between flanges; for precision, cylindrical, centerless, or surface grinding applications, the hole dimension (H) should not be greater than two-thirds of the wheel diameter (D).

• For other applications OSHA advises the maximum hole size should not exceed one-half the wheel diameter. See 1910.241(b)(10).

Under 1910.241(d)(1) a jack is an appliance for lifting, lowering, or moving a load by applying a pushing force (types include lever and ratchet, screw, and hydraulic), and under 1910.241(d)(2) the jack’s "rating" is the maximum working load it is designed to lift safely throughout its specified travel.

• Practical advice: follow the manufacturer’s instructions on point of load, applied force, and lever arm to ensure you do not exceed the jack’s rated capacity. See 1910.241(d)(1) and 1910.241(d)(2).

Under 1910.241(b) and the definition in 1910.241(b)(6) an employer must ensure abrasive wheels are used with appropriate safety guards that enclose and restrain wheel pieces and provide protection if a wheel breaks.

• Practical steps: verify guards match the wheel type and mounting (see wheel type definitions in 1910.241(b)), inspect guards for damage, and ensure guards are secured before operating grinders. See 1910.241(b)(6).