UL 62841-3-4-2016 pdf download – Electric Motor-Operated Hand-Held Tools, Transportable Tools And Lawn And Garden Machinery – Safety – Part 3-4: Particular Requirements For Transportable Bench Grinders.
19 Mechanical hazards This clause of Part 1 is applicable except as follows: 19.1 Replacement ofthe first paragraph: Moving and dangerous parts other than the accessories shall be so positioned or enclosed to provide adequate protection against personal injury. The guarding of accessories is covered in 1 9.1.101 through 19.1.103. For grinding wheels and wire brushes, a guard in accordance with 19.1.101 and 19.1 .102, a work rest in accordance with 19.1.102 and a transparent screen in accordance with 1 9.1.103 shall be provided. For polishing wheels, a guard, a work rest and a transparent screen are not required. Guards for accessories shall not be removable without the aid of a tool. 19.1.101 Guards The guard shall cover the periphery and the sides of the accessory, flanges and the end of the tool spindle, except a portion of the accessory as allowed in 19.1.102 and indicated in Figure 102. The guard shall be designed so that the tool spindle cannot be fitted with an accessory greater than 1,07 times the maximum diameter marked on the tool. The guard shall be constructed so that removal of the peripheral protecting member is not necessary for replacement of the accessory. Compliance is checked by inspection and by measurement.
19.105 Direction of accessory rotation The periphery of all accessories shall move in a downward direction with respect to the operator’s position. Compliance is checked by inspection. 19.106 Eccentricity of the tool spindle and flange The eccentricity of the tool spindle shall be less than 0,1 mm. For tools that provide for mounting of the accessory through the flange or similar clamping and locating device, the total eccentricity of the combination of the tool spindle, the diameter of the flange bore and the diameter of the part of the flange which locates and guides the accessory shall be less than 0,3 mm. Compliance is checked by measurement. The eccentricity of the flange in the worst off-centre position allowed by the mounting procedure is measured. 19.107 Out of balance A bench grinder intended for use with grinding wheels of 100 mm or more in diameter shall have adequate strength when out of balance. Compliance is checked by the following test. A simulatedgrinding wheelhaving a diameterequalto the maximum diametermarkedon the toolspindle in accordance with 8.3 is mounted on the tool spindle. The bench grinder is then to be operated at no-load for 250 000 revolutions. The simulated wheel may consist ofa circular steel plate. The simulated wheel is to be out ofbalance, by the addition or removal ofmaterial: – for wheels less than 150 mm in diameter, by d 2 /1 607 Nmm, where d is the diameter ofthe wheel in mm; – for wheels of150 mm or more in diameter, by 14 Nmm. After the test, the tool shall withstand the electric strength test of Annex D between live parts and accessible parts and live parts shall not have become accessible as specified in Clause 9. In addition, all guards shall remain intact.