Type of Mechanism in Back Hoe

AFIK there are three hydraulic cylinders required to operate a back hoe. One to raise/lower the upper arm with respect to the crawler or base (JCB? whatever that is). One to extend/retract the lower arm. A third to rotate the bucket. All connections are forms of clevis joints.

I think a single cylinder bell crank would be limited to less that 180 degrees.

JCB is a British brand of back hoe, marketed by a lot of Cat dealers 25 years ago before Cat came out with their own back hoe.

I believe that the mechanism you are referring to does indeed allow the bucket to swing 180 degrees or more. It also gives the cylinder the greatest leverage where it is needed most, when the bucket is cutting the ground. Thirdly, it partially evens out the speed of rotation of the bucket through the full stroke of the cylinder.

Here is a picture of a toy bachoe for anybody who needs to look at the mechanism:

http://us.st11.yimg.com/us.st.yimg.com/I/toytruckcity_1933_10344902

Someone smart on back hoes go to Google and click "Images" and then type in "JCB Backhoe" and all types of pictures come up. Maybe then you can help this guy. I am a dumb old diesel engine guy (not heavy equipment smart) and the only thing we need back hoes for is to keep the engine up out of the dirt (support assembly for the engine).

OK. S.A. In a nutshell:"

Success Stories

Hydraulically-driven Backhoe Arm

An off-road vehicle manufacturer used EASY5 to model a new hydraulically-driven backhoe arm design.

This model was used to determine component sizing, given a performance specification. Several alternative configurations were quickly evaluated and eliminated from consideration since the design did not meet the performance requirements.

The backhoe arm design consisted of three actuators that control both the motion of the arm and the dump bucket. The hydraulic control system of the model was built in EASY5 using the Thermal Hydraulics Llibrary.

The backhoe mechanism was modeled using a multibody dynamics program, which calculates position and velocity of the mechanism while EASY5 calculates the forces acting on the mechanism.

US Patent describes it in full at:<http://www.patentstorm.us/patents/5125787-description.html>

Whether or not it allows 180 deg. rotation of the bucket is open to confirmation.

PS: Ever hear of "<DOGPILE.COM>" ???

Is it a Spinoff from an old Disney Film song sung by Dwarves? Hi Hoe Hi Hoe ?????

Seriously, why is it called a Back Hoe in the USA???? I believe they have various names in the UK like Trench digger etc etc. Which to my mind, describe more accurately its usage.

I am still annoyed by stupid US designed online tests from the US company I worked for where NOBODY in Europe knew what a back Hoe was at that time!! So we all got that answer wrong!!

It was a computing company by the way, not Caterpillar or similar!!!!

Andy Germany "Seriously, why is it called a Back Hoe in the USA???? I believe they have various names in the UK like Trench digger etc etc. Which to my mind, describe more accurately its usage."

Years ago there were Steam Shovels which moved the scoop outward and upward. The rear dropped down when the latch was released to drop the load. The bucket could be mounted in reverse to scoop up the load as it moved toward the base of the crawler mounted power section. It released the load by being raised upward, the rear being closed. Main boom and scoop or bucket arm, no fancy linkage other than being able to rack the bucket arm to longer or shorter positions with respect to the main arm.

My WAG is that in the second mode it was called a back hoe type of operation.

juba-jabba is correct re: four bar linkage. I overlooked it. Mea Culpa!

I've heard them called "four-bar-linkages" They will indeed allow the output link to swing in excess of 180 degrees without any links going through a toggle point. As mentioned earlier here, the proper design of this four bar linkage will promote joint life by reducing peak forces as it provides a controlled speed through the range of motion.

Best of luck with your sun tracking platform.