Zhuzhou Jiabang Refractory Metal Co., Ltd |
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Tungsten Crankshaft balance weight ASTM B 77707
Tungsten balancing weight used for Crankshaft
Structure of Tungsten Alloy Crankshaft
(1)Antiscuffing. The bearing surface should be able to absorb
enough oil to keep it from scuffing during startup, or any other
time when it must run momentarily without an oil supply.
(2) Embedabillty. The surface of the bearing must be soft enough to
allow particles of foreign matter to embed themselves and prevent
damage of the shaft journal.
(3) Conformability. The bearing must be able to conform or fit
itself to the surface of the crankshaft Journal.
(4) Conductivity. The bearings must be able to conduct heat to the
connecting rod so that they will not overheat.
(5) Resistance to Heat. The bearing must be able to maintain all of
these characteristics throughout its entire operating temperature
range.
a. Connecting Rod Lubrication. The connecting rod bearings fit into the lower end of the connecting rod. They are fed a constant supply of oil through a hole In the crankshaft Journal. A hole in the upper bearing half feeds a passage In the connecting rod to provide oil to the piston pin.
b. Crankshaft Main Bearings (Fig. 3-44). The upper halves of the main bearings fit right into the crankcase, and the lower halves fit into the caps that hold the crankshaft in place. The main bearings have holes drilled in their upper halves through which a supply of oil is fed to them. The tungsten alloy crankshaft has holes drilled in the journals that receive oil from the main bearings to feed the rod bearings. It is a common practice to cut a groove In the center of the main bearing Inserts. This supplies a more constant supply of oil to the connecting rod bearings. One of the main bear- Ings also serves as a thrust bearing. This controls back and forth movement of the crankshaft. This thrust bearing Is characterized by side flanges.
General. The flywheel stores energy from the power strokes, and
smoothly delivers it to the drive train of the vehicle. It mounts
on the end of the crankshaft, between the engine and the
transmission.
b. Manual Transmission. When the vehicle Is equipped with a manual
transmission, the fly- wheel serves to mount the clutch.
Automatic Transmission. When the vehicle Isequipped with an
automatic transmission, the flywheel serves to support the front of
the torque converter. On some configurations, the flywheel is
combined with the torque converter.
d. Starter Ring Gear. The outer edge of the flywheel Is lined with
gear teeth. They are to engage the drive gear on the starter motor.
e. Construction. The flywheel on large, low- speed engines usually
is made of cast iron. This Is desirable due to the heavy weight of
the cast Iron, which helps the engine maintain a steady speed.
Small, high-speed engines usually use a forged steel or forged
aluminum flywheel for the following reasons.
(1) The cast iron is too heavy, giving it too much inertia to allow
the speed variations necessary on small engines.
(2) Cast iron, because of its weight, will pull itself apart at
high speeds due to centrifugal force.
The crankshaft, sometimes casually abbreviated to crank, is the
part of an engine which translates reciprocating linear piston
motion into rotary motion. To convert the reciprocating motion into
rotation, the tungsten alloy crankshaft has "crank throws" or
"crankpins", additional bearing surfaces whose axis is offset from
that of the crank, by which the "big ends" of the connecting rod
for each cylinder attaches and imparts its downward motion into the
shaft.
It typically connects to a flywheel, to reduce the pulsation
characteristic of the four-stroke cycle, and sometimes a torsional
or vibrational damper at the opposite end, to reduce the torsion
vibrations often caused along the length of the tungsten alloy
crankshaft by the cylinders farthest from the output end acting on
the torsional elasticity of the metal.