Doosan G643, Руководство по обслуживанию

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G643 (E) Service Manual Chapter 3. Engine Mechanical System 88
Figure 12-53 Measuring Valve Spring Tension
Figure 12-54 Measuring Valve Spring Length
Repair
Figures 12-55 through 12-58
Valve Grinding
Pitted valves must be refaced to the proper angle.
Valve stems that show excessive wear, or valves
that are warped excessively must be replaced.
When an excessively warped valve head is refaced,
a sharp or thin valve margin may result because of
the amount of metal that must be removed.
Undersize valve margins lead to breakage, burning,
or preignition due to heat localizing on this knife
edge (figure 12-55). Refer to “Specifications”. If the
edge of the valve head is less than specification
after grinding, replace the valve.
Several different types of equipment are available
for refacing valves. The manufacturer's instructions
for how to use the equipment should be carefully
followed to attain the proper results.
Figure 12-55 Valve / Seat Grinding
Figure 12-56 Critical Valve Dimensions
Figure 12-57 Measuring Valve Seat Concentricity