I have a question about a pulley system project
I am building a platform lift. I am using a 16 ft long by 21″ wide plank. I am using a 8 pulleys in this system. See photo here:
http://i186.photobucket.com/albums/x309/scottmn_photo/items/platform.jpg
I want the platform to raise up level. Is this the optimal set up? Is there another configuration (using more or less pulleys) that would be better.
Thank you kindly in advance,
Scott
He made it clear what he meant by better – “I want the platform to raise up level”. I’ve been thinking about a similar problem and had the same question.
Scott:
To determine if the system is better you must define better.
To lift the platform one inch the rope will have to be pulled 8 inches.
If the motor for the which is able to handle higher loads then you might have a better system by reducing the number of pulleys. By doing that the system will lift faster. The system will raise 25% faster with the same speed on the wench drum.
If on the other hand going to more pulleys will result in your ability to use a lower cost and smaller wench going to more pulleys.
Niel Leon
Community Developer – Engineering.com
Tim:
As proposed if the system is designed so that
1. All lengths of the cables between the top and bottom plate are the same
2. All the frictions on all the pulley axles are the same
3. You pull on the two cables equally with the same tension
the system should go up level. The challenge may be to get all those design constraints to happen at once.
I notice that the top and bottom pulleys are not equally spaced and the up cables are no the same length as the down cables. This may be some of the reason why you are not getting maintain level lifting.
An alternate consideration would be to use for cable one at each corner. This would eliminate the issue with having unequal lifting and may help to keep it level. I am now assuming that keeping the system level is the only problem that needs to be resolved.
Niel
