LO 8-4 Explain the purpose and methods used to increase the rigidity and strength of a diesel engine cylinder block

1.3. Ladder-Frame Blocks

Ladder-Frame Blocks

Some newer engine designs are incorporating ladder-frame crankcase reinforcement as a construction feature. Like other crankcase reinforcement techniques, which can strengthen a block while reducing weight, noise, and vibration, ladder frames provide an additional structure. In ladder-frame blocks, the sides of the block extend exactly to the centerline of the crankshaft bearing bore. A separate, additional ladderlike section of the block structure, called a ladder frame , attaches to the crankcase oil pan rails on one side and to the oil pan on the other. The main bearing caps are integrated into this single piece, lower section of the block (Figure 30 and Figure 31). Removing one main bearing cap requires removing the entire ladder frame because it is formed with all the main bearing caps. The ladder frame may also contain balance shaft housings and the oil pump. Ladder frames considerably improve block rigidity and strength, but they also can add to the cost and complexity of an engine. Another drawback, depending on construction technique, is the potential for leakage in the gasket joint created by the device. Engine crankshaft bearings cannot be serviced in frame or in chassis. Removal and replacement of a crankshaft bearing requires complete removal of the engine from the vehicle Figure 32.

FIGURE 08-30: The ladder-frame block incorporates the main bearing caps into a single structural component resembling the rungs of a ladder. The frame supports the crankshaft and adds structural rigidity and strength to the block while reducing noise and vibration.

FIGURE 08-31: This 6.0 L (366 in 3 ) ladder-frame block uses a two-piece crankcase. The upper section incorporates the main bearing caps into the crankcase structure.

FIGURE 08-32: The exterior view of a ladder frame forming the crankcase.