1.1 Penetrometer, similar to the instrument illustrated in Fig. 1, designed to measure in tenths of a millimetre the depth to which the standard (or optional) cone falls into the grease. The cone assembly or the table of the penetrometer shall be adjustable to enable accurate placement of the tip of the cone on the level surface of the grease while maintaining a zero reading on the indicator. When released, the cone should fall without appreciable friction. Both the penetrometer shaft and the rack engaging the measuring dial should be at least 62.0 mm in length. If only penetrations less than 400 are to be measured, the penetrometer may be designed such that, when released, the cone falls for at least 40.0 mm. The tip of the cone should not hit the bottom of the sample container. The instrument shall be provided with leveling screws and a spirit level to maintain the cone shaft in a vertical position.
1.1.1 Automatic Penetrometers, which include such devices as timers, electrical release mechanisms, digital depth indicators, and contact sensors are permitted, so long as the results obtained with such instruments are shown to fall within the precision in accordance with 13.2.
1.2 Standard Cone, for measuring penetrations up to 475, consisting of a conical body of magnesium or other suitable material with detachable, hardened steel tip, shall be constructed to conform to the tolerances in accordance with Fig. A1.1. The total mass of the cone shall be 102.5 more or less 0.05 g and that of its movable attachments shall be 47.5 more or less 0.05 g; the attachments shall consist of a rigid shaft having a mechanical stop at its upper end and suitable means, at the lower end, for engaging the cone. The interior construction of the cone can be modified to achieve the specified weight, provided that the general contour and weight distribution are not altered. The outer surface of the cone is to be polished to a smooth finish. A surface finish in the range from 0.10 to 1.12 µm (4 to 44 µin.) root mean square (RMS) has been found to have no measurable effect on penetration results.
1.3 Optional Cone, for measuring penetrations up to 400, consisting of a conical body of brass or corrosion-resistant steel with detachable, hardened steel tip, shall be constructed to conform to the tolerances shown in Fig. A1.2. The total mass of the cone shall be 102.5 more or less 0.05 g and that of its movable attachments shall be 47.5 more or less 0.05 g; the attachments shall consist of a rigid shaft having a mechanical stop at its upper end and suitable means, at the lower end, for engaging the cone. The interior construction of the cone can be modified to achieve the specified weight, provided that the general contour and weight distribution are not altered. The outer surface of the cone is to be polished to a smooth finish. A surface finish in the range from 0.18 to 1.50 µm (7 to 59 µin.) RMS has been found to have no measurable effect on penetration results.
1.4 Grease Worker, consisting of a grease cup, cover, and plunger assembly and conforming to the dimensions given in Fig. A1.3. The dimensions not shown may be altered and other methods of fastening the lid and securing the worker can be used. The worker can be constructed for either manual or mechanical operation.
1.5 Grease Worker Drive, Manual, similar to that shown in Fig. A1.4. The design must be such that a rate of 60 more or less 10 strokes per minute with a minimum length of 63 mm (2 7/16 in.), can be maintained.
1.6 Grease Worker Drive, Motorized, similar to that shown in Fig. A1.5. The design must be such that a rate of 60 more or less 10 strokes per minute with a minimum length of 63 mm (2 7/16 in.), can be maintained. The mechanical grease worker must be provided with a presetting counter to permit the apparatus to be automatically stopped after any required number of double strokes up to 99 999.
1.7 Grease Cutter, having a sharp, rigidly mounted, beveled blade, shall be essentially as shown in Fig. A1.6. It is necessary that the blade be straight and sharpened, as shown.
1.8 Overflow Ring (optional), conforming in principal to the illustration in Fig. A1.3 is a useful aid for returning displaced grease to the worker cup. The overflow ring shall be positioned at least 13 mm (1/2 in.) below the rim of the cup while making a penetration measurement. A rim 13 mm high is helpful.
