Maintenance Strategy Based on Reliability Analysis and FMEA: A Case Study for Hydraulic Cylinders of Traditional Excavators with ERRS

Table 8

FMEA for new HC from HE with ERRS.

Failure part	Potential modes	Likely failure cause	Detect result			RPN	Weight	Countermeasures
HC	Crack	Overload	N
		Excessive internal pressure in cylinders	N
		Encounter external impact	Y	8	8	64		Add protective board on the top of HC which suffer intense impact easily
	Leakage	Insufficient coating thickness results in corrosion	N
		Weld defect	N
		Instantaneous high pressure causes the damage of the seal	Y	7	10	70		Reduce the instantaneous high pressure caused by energy released from accumulator to the system
		Continuous operation for a long time	N
		Improper assembly and disassembly	N
	Abrasion	Bad working condition result hydraulic oil mixed with impurities	N
		Unreasonably kinematic pair clearances	Y	7	9	63		Improve assembling accuracy and strengthen the final inspection
	Creep	Low assembling accuracy	N
		Hydraulic oil pollution causes the stagnation of the valve spool	Y	8	10	80	∗∗∗∗∗	Check the cleanliness of the hydraulic oil at regular intervals, timely replacement