Crankshaft Slot
The crankcase is divided into two sections in a longitudinal plane. This division may be in the plane of the crankshaft so that one-half of the main bearing (and sometimes camshaft bearings) are carried in one section of the case and the other half in the opposite section. [Figure 1] Another method is to divide the case in such a manner that the main bearings are secured to only one section of the case on which the cylinders are attached, thereby providing means of removing a section of the crankcase for inspection without disturbing the bearing adjustment.
Crankshaft Storage Bag
I did my best to immobilize the crankshaft pulley/hb while tightening the crankshaft bolt. Well I didn't get near enough torque on it. Now after getting A REAL MECHANIC to get the hb off with a torch, I got problems. I need to replace the hb, gear and damaged belt. The keyway is not a slot anymore, but a valley. Photo: Inside a shaver: A crank-like mechanism (a peg that engages in a slot) moves one of the cutting blades back and forth. The top photo shows a typical electric shaver as you look down on it; the bottom photos show you what you see when you pull the blades away for cleaning. If your crankshaft is worn beyond OEM specifications, scratched or has experienced excessive heat, a rebuild or new crankshaft is required. ProX Racing Parts has the quick and easy solution offering a true drop-in ready crankshaft, fully assembled to OE specifications.
Figure 1. Typical opposed engine exploded into component assemblies |
Crankshaft Slotted
A crankshaft may be of single-piece or multipiece construction. Figure 2 shows two representative types of solid crankshafts used in aircraft engines. The four-throw construction may be used either on four-cylinder horizontal opposed or four-cylinder inline engines. The six-throw shaft is used on six-cylinder inline engines, 12-cylinder V-type engines, and six-cylinder opposed engines. Crankshafts of radial engines may be the single-throw, two-throw, or four-throw type, depending on whether the engine is the single-row, twin-row, or four-row type. A single-throw radial engine crankshaft is shown in Figure 3. No matter how many throws it may have, each crankshaft has three main parts—a journal, crankpin, and crank cheek. Counterweights and dampers, although not a true part of a crankshaft, are usually attached to it to reduce engine vibration.
Figure 2. Solid types of crankshafts |
Figure 3. A single-throw radial engine crankshaft |
Centrifugal force threw these substances to the outside of the chamber and kept them from reaching the connecting-rod bearing surface. Due to the use of ashless dispersant oils, newer engines no longer use sludge chambers. On some engines, a passage is drilled in the crank cheek to allow oil from the hollow crankshaft to be sprayed on the cylinder walls. The crank cheek connects the crankpin to the main journal. In some designs, the cheek extends beyond the journal and carries a counterweight to balance the crankshaft. The crank cheek must be of sturdy construction to obtain the required rigidity between the crankpin and the journal.
In all cases, the type of crankshaft and the number of crankpins must correspond with the cylinder arrangement of the engine. The position of the cranks on the crankshaft in relation to the other cranks of the same shaft is expressed in degrees.
The simplest crankshaft is the single-throw or 360° type. This type is used in a single-row radial engine. It can be constructed in one or two pieces. Two main bearings (one on each end) are provided when this type of crankshaft is used. The double-throw or 180° crankshaft is used on double-row radial engines. In the radial-type engine, one throw is provided for each row of cylinders.
Crankshaft Balance
Dynamic Dampers
The construction of the dynamic damper used in one engine consists of a movable slotted-steel counterweight attached to the crank cheek. Two spool-shaped steel pins extend into the slot and pass through oversized holes in the counterweight and crank cheek. The difference in the diameter between the pins and the holes provides a pendulum effect. An analogy of the functioning of a dynamic damper is shown in Figure 4.
Figure 4. Principles of a dynamic damper |
RELATED POSTS
Connecting Rods
Pistons
Cylinders
Firing Order
Valves