SPECIAL AR 3312292 - Caterpillar

The 6V7898 Dial Bore Gauge Group permits measurements to be taken in diameter ranges of 50.0 to 200.0 mm in increments of 0.002 mm. The gauge has a depth range of 13 to 300 mm. This high degree of accuracy is needed, especially in applications such as the measurement of connecting rod bores.
This is a precision instrument. Always be careful when using the gauge to prevent damage and/or loss of adjustment to the instrument. Always use the procedure shown in this instruction to adjust the dial bore gauge. Always remember that the gauge and the part being measured must be approximately the same temperature or the readings will not be accurate.
Components Of 6V7898 Dial Bore Gauge Group
1. Dial Bore Gauge.2. Storage Box.3. Gauge Points with Locknuts.4. Gauge Point Extensions.5. Hex Wrenches.6. Indicator Finger Ball Tool.7. Gauge Point Ball Tool.8. Wrench.How To Use The 6V7898 Dial Bore Gauge Group
(1) Find the correct gauge point, using the table below. For example, if the bore to be measured has a diameter of 114 mm, use gauge point no. 7 + 2.(2) Install the correct gauge point (1) in the dial bore gauge. Carefully put gauge group (2), with gauge point, into the size setting fixture. See Form SMHS8254 for adjustment procedure. Adjust spindle (3) until it reads the exact size being set.(3) Adjust gauge point (1) until indicator hand (4) is at the 12 o'clock (straight up) position, and counter hand (5) is at "0" position. Use wrench (6) to tighten locking nut (7) to hold gauge point (1) in the adjusted position.(4) Again put the dial bore gauge into the size setting fixture. To zero the dial indicator, loosen bezel screw (8). Move the indicator back and forth as shown, until the minimum reading is obtained. Reset zero as necessary by turning bezel (9), then tighten bezel screw (8).(5) Put the dial bore gauge into the bore that is to be measured and work the gauge back and forth to get the minimum measurement. Any reading other than zero, is the amount of deviation, plus (+) or minus (-), from the size for which the gauge was originally set.Adjustment Of Centralizer Points
(1) For maximum accuracy, the centralizer points must be in firm contact with the wall of the bore being measured.(2) Put 1.98 mm hex wrench (1) in centralizer stop adjustment (2), and turn the stop adjustment with the wrench to adjust centralizer points (3) so they are firmly in contact with the wall of the bore being checked.(3) Slide the gauge head IN and OUT of the bore several times to check the adjustment. The more near the centralizer points are set to the actual bore size being checked, the easier it will be to put the gauge into the bore. The centralizer points must always make contact with the sides of the bore.Adjustment Of Worn Centralizer Points
When the centralizer points (1) become worn, they must be adjusted to keep accuracy. Always adjust both points at the same time.