I have a project that requires a robotic arm to lift an empty trash bin of about 20-25 pounds (about a 90 gallon bin). Now this arm will be fitted on a back of a truck bed. The concept is to pick up an empty barrel and clean it from the sidewalk or curb in front of a household.
Where could I find designs or something to help me out with this phase of my project?
You probably need to start out with a hydraulic gizmo like below and then add a gripper and remote controls.
he could always use linear actuators which might i add are much cheaper than that beast
there are some linear actuators that are cheap about 90 bucks a pop with 110 lbs lifting capacity
110 lbs for 90$$? What a deal! 
The tradeoff is probably speed of operation.
We used to use long-throw motorized jacks like that for satellite dish positioning. One of them could swing our 8-foot solid aluminum dish, in its welded steel cradle, from one end of the geostationary arc to the other without breaking a sweat, by pushing or pulling on a lever that was effectively only about a foot and a half long.
It took most of a minute to run the full arc endpoint to endpoint, though.
I have never used linear actuators so it is a surprise to me on how strong they are and how cheap as well, thats so cool. So I geuss they work somewhat like a hydrolic system.
There are several ways to get linear motion from a rotary motor, but the one I’ve seen most often is to use the motor to turn a long threaded rod. The motor and rod are mounted on one half of the actuator, and the nut that rides on the rod is mounted to the other part. As the motor spins, it applies geared-down torque to the screw, which, as long as the screw is kept from rotating freely, rides in and out, lengthening and contracting the overall length of the actuator, much like the lengthening and contracting of a hydraulic cylinder. They can produce a lot of force, though they tend to operate somewhat slowly, since they’re spinning a nut up and down a long threaded rod.
If you perform a google image search for “linear actuator”, you can see a number of examples of this type of motorized jack. They’re typically shaped like a telescoping tube or box-beam, with a motor and gearbox at one end.
Oh, thanks! 
And BTW Vistro, sorry for hijacking this thread…
surpluscenter.com/sort.asp?UID=2006121819480315&catname=electric&keyword=EALD
there are the linear actuators, and if he wants to go the hydraulic route, there are pumps and cylinders on that site too, excellent pricing i think