Yaroslavl ???-236, Maintenance Manual

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2 Technical characteristics for repair
2.1 General terms and definitions
Serviceability means suitability of the object (item) for prevention and detection of the
causes of failures and damages, keeping and restoring of the operational condition with the help of
maintenance and reparation.
Repair means a complex of actions aimed at recovery of order and working capacity of
the items and recovery of their resources or components.
Repair types:
Current repair is a kind of repair which is performed for maintaining or recovery of
working capacity of the item with the decrease of its operational characteristics (capacity,
efficiency and others) which includes the replacement or recovery of defective parts with the help
of metal-mechanical works with minimum labour intensity (thread recovery, correction and
others), malfunctions repair occurred during the operation.
Current repair is the repair aimed at recovery of the engine with the help of removal of
detected and foreseen localized troubles (defects) and objective confirmation of the working
condition of the engine at the moment, as well as possibility of its storing before the regular
check of its technical condition or main repair.
During the current repair engine is disassembled in the volume necessary for receiving
access to the defective parts, nods and units.
Timely performance of the current repair helps to decrease the necessity of main
repair and increase run life of the vehicle.
Current repair should provide the failure-free operation of the repaired units and nods with
the run life no less than to the next regular maintenance.
During the current repair troubles are removed due to the replacement and repair of the
separate nods and parts, except basis ones. The basis parts are: cylinders cast in block, crankshaft,
flywheel of the transmission gear box. Thus, during the current repair it is allowed to replace piston
rings, piston pins, bushings, cylinder head gaskets, bushing collars, as well as
troubleshooting: for example, valve gaping to the seats can be removed with the help of valves
seating or seats grinding.
Main repair means the repair which is performed for recovery of the engine operability
(operational characteristics) and for provision of its capacity no less than 80% of the capacity of
the new engine with the replacement and recovery of cylinder block/crankshaft and other parts
with the help of mechanical treatment, welding, build up welding, heat treating and others. Main