• Transactions of The Korea Fluid Power Systems Society
• /
• v.5 no.2
• /
• pp.14-19
• /
• 2008

Hydraulic excavator consists of booms, arms, bucket, and cylinder. The cylinder make these structures moved and the cushion parts of cylinder in operation absorb the great impact which is stemmed from high velocity and pressure at cushion parts of cylinders. The cushion technology of cylinders has a great effect on the operator's comfortable as well as protecting equipment from damage by suppressing the inertia of the hydraulic excavator. In this study, three hydraulic cylinders have different shapes of a cushion ring, respectively. we studied optimal cushion pattern by analyzing the change of cushion pressure and time, according to supply pressure and velocity variations.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1333-1334
• /
• 2011

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.3
• /
• pp.95-103
• /
• 2010

This paper presents a simulation model of a double-acting high-speed pneumatic cylinder with a relief valve type cushion mechanism. The model predicts piston motion, mass flow rate, pressure and temperature time histories of cushion chamber. Of interest here is to investigate the cushioning effect of varying the piston and piston-rod diameter, cushion ring diameter and length, and stoke in cushion mechanism. As a result, this cushion mechanism is found to be adequate under high-speed driving of pneumatic cylinders. The simulation model proposed here will be very useful to analyze the dynamic characteristics and to improve or design the better cushion mechanism in high-speed pneumatic cushion cylinders.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.12
• /
• pp.1901-1907
• /
• 2010

A hydraulic cylinder is a primary component of an excavator and is used for activating attachments such as boom, arm, and bucket. Generally, the cylinder is prone to structural problems such as buckling and fatigue failure caused by cyclic high pressure. Therefore, the safety margin for fatigue, yield, and buckling during the design lifetime should be evaluated at the durability-design stage. The durability design includes basic and detailed stages. In the basic design, the principal dimensions of the rod and tube are determined by considering the working force, speed, and range with respect to yield and buckling. In the detailed design, the dimensions of the rod notch, welds, tube end, gland, orifice, and cushion ring are determined by considering the fatigue safety. We present and discuss the overall procedure for durability design and the related analysis techniques.