I'm new here, so i can't open my own topic, and I'm in need for help!!!! Can anyone tell me,can I calculate or what value to use....I need to know a damping coefficient of a two-way hydraulic cylinder. I need it for a project on my university (I'm a student), cause I have a telescopic boom forklift (teletruk),and I must calculate it's vibrations. I calculated the stiffness coefficient of a telescopic boom, but don't know anything about damping coefficient (does a standard two-way hydraulic cilinder have one??)..please direct me to some help...thank you!!
Welcome to the forum. You certainly ask some challenging questions. I took a couple of courses once at Wainbee in Toronto, Ontario. These people handle design and troubleshooting problems and perhaps would communicate with you. My teachers name at the time was Ted Groves and I think he would give you the references you need. I remember his laptop background was his beautiful cottage up north. Include this text in your e-mail if you wish; hope this link works, good luck. Phil http://www.wainbee.com/training/techTalk.asp
Leo, welcome to Heavy Equipment Forums. I moved your question to a thread of its own, here in General Industry Questions. I agree with Phil--that's a tough one. Perhaps somebody will be able to help you out.
I cant give you the coefficent, but it would be based on cylinder size, and some other variables. However, you could make an argument that the value is zero since hydraulic fluid or water is not compressible, the steel of the cylinder will not shrink under pressure, and there fore, any dampening will cause the ram of the cylinder to buckle. I know that probably doesnt help you much, but something to keep in mind.
I've worked on hydraulic systems for a long time and haven't heard that particular term used in relation to just a hydraulic cylinder. When I went through the various schools over the years I was told hydraulic oil is theoretically not compressible. So if by damping you mean able to absorb shock, then there is none. There is an amount of drag involved with moving a fluid lubricated piston with synthetic material for seals in a barrel with a specific grade of finish. Perhaps damping might mean the amount of power absorbed overcoming friction in the barrel. I would have no idea how to calculate that and I know for a fact that it changes with the temperature of the oil or as the seal material wears out. I usually consider damping as an affect attained when using an accumulator to absorb motion. Shock absorbers in an auto would be one type of use. Ride control in the bucket circuit of a wheel loader and ride height control in an articulated truck are two common types of damping. You also mentioned a telescoping cylinder in a forklift. I have never worked on a forklift with a double acting cylinder. All I have seen only extend and use gravity to retract them. Articulating dump trucks usually use double acting telescoping hydraulic cylnders because the box raises past ninety degrees and has to be pulled back over center before for gravity will return them. A little more info and we might be able to help.