Engine Mounted Components Structure and Characteristics

Mounted components, also known as engine block components, are the parts that remain relatively stationary during engine operation. These mainly include: crankcase, tappets, oil pan, flywheel housing, accessory brackets, cylinder liners, cylinder head, crankcase ventilation system, etc. The entire engine is assembled based on these components.

Crankcase Assembly

I. Function and Requirements of the Crankcase:

The crankcase is one of the most important and fundamental fixed components of an engine. Its main functions are: to support almost all the parts of the diesel engine, ensuring they maintain accurate relative positions during operation and guaranteeing normal engine operation; to provide lubrication passages, ensuring necessary lubrication and cooling for all moving parts; and to serve as the mounting reference for the diesel engine, securing it to the chassis or base.

During operation, the crankcase bears significant static and dynamic loads, operating under harsh conditions. Therefore, to ensure safe, reliable, and durable engine operation, the crankcase must possess sufficient rigidity and strength. The dimensions should be small, the weight light, and the structure as simple as possible. Furthermore, it should be easy to manufacture, and noise reduction requirements must be considered.

II. Crankcase Structure and Characteristics: The B/FL413F air-cooled engine crankcase assembly can be considered to consist of four main parts: the crankcase body, the transmission case cover, the main bearing cover, and the main oil passage pipes.

(I) Transmission Case Cover: The B/FL413F air-cooled diesel engine uses a rear-mounted helical gear transmission mechanism, with the transmission gear chamber cast integrally with the crankcase body. For mounting and dismounting the transmission gear, a transmission case cover is located on the upper part of the transmission gear chamber at the rear of the crankcase. The transmission case cover has mounting holes for the fan drive shaft, hydraulic pump, fuel injection advance mechanism drive shaft, and, for special models, the V-type twin-cylinder compressor.

To ensure accuracy, the important coordinate holes on the transmission case cover are machined after assembly with the crankcase body. The transmission case cover is fastened to the crankcase body with bolts and positioned using locating pins.

There are various types of transmission case covers. For example, automotive transmission case covers have a hot air outlet device, with a window and corresponding screw holes at the top for installing the hot air outlet. For engines such as generator sets, there is no hot air outlet, and the top is sealed. Another type of transmission case cover has a protruding top, an angled hot air outlet, and mounting holes for a twin-cylinder V-type blower. Regardless of the structure, the main installation dimensions of the transmission case cover are the same; the differences are only in a few specific parts. Transmission case covers are made of gray cast iron.

(II) Crankshaft Housing: The upper part of the housing consists of two cylinder liner mounting planes with an included angle of 90°, forming a 45° angle with the oil pan. Cylinder liner holes with a center distance of 165 mm and a diameter of 139 mm are arranged on these planes. Because the B/FL413F engine uses a parallel connecting rod mechanism, the left and right cylinder bores are not on the same centerline, offset by 29 mm. The cylinder liner is positioned to the crankcase via end faces and stops, and secured to the crankcase along with the cylinder head using three flexible through bolts.

At the rear of the cylinder liner plane (viewed from the flywheel end), there is a mounting hole for the main oil passage pressure regulating valve, used to adjust the main oil passage pressure. Additionally, at the rear of the cylinder liner plane, there is an oil outlet for the cab heating system; for models without a heating system, this hole is sealed with a plunger.

For turbocharged models, there is one turbocharger lubricating oil return port each on the rear of the left and right cylinder liner planes; non-turbocharged models do not have this port.

In addition to the above, the cylinder liner plane also has a cylinder head oil return hole and auxiliary screw holes.

Above the cylinder liner plane are the protective tube holes; pushrods pass through the protective tubes, which are sealed to the crankcase with O-rings. It should be noted that the included angle between the two rows of protective tube (pushrod) holes is not 90°, but 97°.