Hi Gary,

You can obtain detailed and accurate answers to your questions from Parker Hannifin. Their web site address is www.parker.com.www.parker.com.

As this is a large web site, you may be better off contacting their customer service department (800) 272-7537 for guidance on Cylinder choice, accumulators, Hydraulic Power Units, et cetera.

Regards, ■

Dear Gary,

If the hydraulic take-up(TU) is to serve as the equivalent to a gravity TU then the TU pulley travel velocity should be in the vicinity of 1 m/s. Dynamic analysis show that a typical 1-2 km long covneyor without significant lift and facric construction will be in this league. Other belt specifications could have variations of this spec.

Regards, ■

WOW, nothing simple in your request.

There are two separate issues you need to address when constructing a dynamic analysis model to obtain the desired result.:

1. what happens when you start (fluid coupling, VFD, across-the-line-start - you gotta control the slack side tension during accelration. What acceleration? Need to know the device and its behavior coupled to the belt including its elastic modulus, idler spacing, system mass details, et al.

2. what happens when you stop (brake, intentional TUP rate of pressure drop, leave in full active mode, synthesize failure modes) - what is the allowable takeup travel, belt tension, belt sag and how the conveyor needs to be controlled due to its feed or discharge differential with other chutes -- like maybe brakes, etc. What happens to the vertical cures lift-off or collapsing to spill material.

All of the above can be solved. It cannot be done on the back of an envelope or in a 10 minute discourse. Your are probably looking at two-three days to quatifiy the various conditions of loading, winter, summer rolling resistance as well as the "what if cases".

I gave you a takeup response ( 1m/s ) based on a reasonable soft start and stop. THis can go to 2 m/s but not much higher with a poorly design conveyor. When you control the takeup you also need to understand the proportional control bandwidth parameters and the dead-band of the load-cell or pressure transducer algorithm.

If you wish this solved in a professional manner beyond free advice, we would be pleased to show what can be determined. I can assure you you question can be resolved.

As a parting note, you can make the take-up power train big enough to do anything. The trick is not to spend big $$. For the example, to control the TUP to 1 m/s it will take over 50 hp on the hydraulic power pack. You will likely then try an accumulator to store some of the stroke and lower the motor size to more or less 5 hp.

Wish you luck, ■

Gary,

Your Drive and Take-Up location helps to minimize your take-up response time requirement, as the belt will tend to maintain its tension from the break-point from your short lift section to the discharge pulley and around to the drive or drive snub (bend) pulley. Note that I am assuming that you have an arrangement where the belt goes from the discharge pulley, to a bend pulley, to the drive pulley, to the take-up pulley, to a take-up bend, and then over or under bend pulleys at the redirection points on its return run to the tail pulley.

As such, the relatively low 1 m/s take-up speed should suffice ? but as Mr. Nordell has stated, a study should be done to confirm this speed. This study can be done by a company, such as Conveyor Dynamics, or by a reputable local (i.e. Toronto conveyor design company). Forums such as this will get you general information (although Larry?s good nature allows him to give valuable details above and beyond the norm) which should not be used without due consideration or confirmation.

Good Luck with your project. ■