New Holland Boomer 20, Руководство по обслуживанию, Страница: 16 / 41

INTRODUCTION
Basic instructions hardware
General
Your tractor has been built using metric hardware.
NOTE: Be sure to use the hardware specified when using tapped holes, as trying to install a metric bolt in an inch
thread, or an inch bolt in a metric thread, will damage the thread.
Certain hardware must be tightened to specific torque specifications. If specific torque specifications are not noted,
tighten the hardware to the standard torque chart specification listed in this manual.
Plating
Hardware used on NEW HOLLAND balers is plated with zinc chromate (gold color). Gold colored hardware has
different torquing requirements from unplated or zinc plated (silver color) hardware because of the difference in the
coefficient of friction of the plating material. The torque charts in this manual list the correct specifications for gold,
silver, and unplated bolts.
Nut tightening
Whenever possible, the nut should be tightened, not the head of the bolt. When tightening using the bolt head, the
clamp load can be lost because some of the torque applied twists the bolt instead of tensioning (stretching) it. The
tension on the bolt is what holds the joint together.
Approximately 90% of the torque applied during assembly goes to overcoming friction between the parts. The other
10% is used to tension (stretch) the bolt. After assembly, the frictional forces disappear, which is the basis for the
saying 'If it does not fail during assembly, it will not fail in service.' The bolt may later fail due to other factors, but not
from being over tightened.
Locknuts
Most locknuts are coated with a special lubricant that is dry to the touch. Anytime a locknut is used, a lower than
normal torque is required. Refer to the torque charts in this manual for specific values.
Jam nuts
When using a jam nut to lock a regular nut, the jam nut should be installed first and tightened to one half the recom-
mended torque, then held in place while installing a regular nut to the recommended torque.
Thread lubrication
The addition of antiseize compound, Molykote, oil, graphite, or any other lubricant to a bolt decreases the friction
between it and a nut. This makes it necessary to reduce the recommended torque to prevent over tensioning of the
bolt. When using the torque charts in this manual, decrease the value by 20% whenever a lubricant is used.
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