Large jaw type rock crushers are very common in the stone and gravel business. They are generally portable and can be towed by tractor trucks. The jaw crusher creates a pinch point that fractures larger rocks and reduces them to about the size of your fist. They are further crushed in a cone crusher and reduced to gravel as small as 1/4 inch.
The jaw crusher has two large flywheels powered by a diesel engine that spins an eccentric which causes a crush plate to oscillate making a pinch point fracturing rocks. The flywheels are indexable and have bolt-on plates to adjust the counterweight size to compensate for wear.
From a balancing standpoint, the crusher acts very much like a one cylinder engine. The counterweights in the flywheels act exactly as the counterweights in a crankshaft. The theory for adjusting the counterweights is identical.
Single cylinder engines are balanced to 50%. That means a bob weight is placed on the crankshaft that represents 50% of reciprocating weight, added to 100% of rotating weight. Reciprocating weight is 50% of, one piston and wrist pin and top of connecting rod, added to 100% the bottom of the connecting rod That weight is clamped to the crankshaft journal. The crankshaft is now balanced with the flywheels and the counterweights are adjusted for phase and amount.
We recently received a call from a customer who makes fiber optic strands. Fiber optic strands are glass tubes that are heated and stretched into long optic fibers that are later incorporated into a data transmission cable. They hired us to help find the cause of a vibration problem in the fan enclosure used in the production of making the fiber optic strands. 
Rotating machinery is everywhere. We are often asked, ”What do you balance?” Rotating machines are responsible for making daily life possible. From heavy manufacturing to high rise building air conditioning – Rotating machinery utilizes high speed moving parts. These high speed moving parts need balancing. Over time those parts may go out of balance and begin to vibrate,causing the machine to run less efficiently. Also if the vibration and imbalance are not properly addressed it can cause adverse conditions on structures and the human environment. Severe vibration causes noise and human fatigue. That’s why there are companies such as ours that can analyze vibration and provide dynamic balancing and mechanical repairs and solutions to eliminate it.
All rotating components create some amount of vibration. When vibration becomes severe it can be very destructive when not corrected. Irregularities or asymmetries created either during the manufacturing process or due to wear are often the cause of vibration. They create a mismatch between the rotating axis established by the supporting shaft and bearings, and the axis of orbit around the actual center of mass of the rotating object. An unbalanced part tries to orbit about this axis of inertia while the shaft and bearings force the part to orbit about the different axis they dictate. This mismatch transmits the forces of vibration into the shaft and bearings, and their support structure causing stress and strain that these systems are not designed to handle.
