Re: limiting FEL MOVEMENT
Ed,
Since the snow blower was originally for a 3 pt mount, then I'll assume it has a PTO drive attachment yoke in the unit's center (left to right). If so, then you could supply a drive line (PTO shaft) to that location. The shaft would need to be supported at the front of the tractor. That front support would be aft of a universal joint which would allow for raising the blower unit.
The amount of lift would be somewhat more than you would normally see at the 3 pt. This is due to my assumption that (on the 3 pt) the distance between the blower and the PTO (on the tractor) is less than the my assumed distance from the loader mounted blower and the proposed PTO location on the front of the tractor.
In other words, if the the blower were at the same distance on the loader as it was on the 3 pt lift, you could lift it approximately that much. The angles in the PTO shaft universal joints can handle that. As a rule of thumb, as long as the u-joint angles, in the loader setup, do not exceed the angles created by the 3 pt lift, you'll be OK.
I think the proposed location for the PTO shaft, front support bearing, would be best if it were to allow the new front u-joint to be in front of any frame or cowling by about 2 inches.
There's one thing that must also be mentioned. PTO shafts, like the one on my 3 pt finish mower, can extend and contract like a slip joint. My mower's PTO shaft can go from 20 inches to about 38 inches. A shaft like that might be necessary in your situation. I think you'd be able to raise the blower with the loader arms about 20 inches before the u-joint angles went to the extremes.
The operation of the loader arms must be limited is some fashion. I think your idea of a chain is perfect. You might consider adding a limit switch to turn on a light for the operator. Also, if $ allows, you can get hydraulic travel limiters that stop the flow of oil when an actuator reaches a specific position. So you could stop the flow of oil to the lift cylinders after they traveled a predetermined length.
What tractor are you putting this on?
Are the hydraulics operated by electric solenoids?
For a couple hundred bucks, you could purchase an electricly operated hydraulic valve that would raise the loader arms a certain amount and then automatically stop raising. An electrical limit switch would supply the signal to the solenoid and tell it to turn off the oil flow, during the raise cycle. The same could be set up for the lowering cycle. That way the operator would flip the switch into the UP position and the blower would raise to its predetermined height and then stop. The switch would then return to the normal "off" position. This is the same concept as used in today's new cars on the driverside window. Hit the switch (but not hold it) and the window goes down all the way down.
Your idea of drive shaft collars, for safety, is good too. I will guess that the IHRA has guidelines for size, spacing, strength etc.
I rather envy your project. My ME senior project was to design and build an antenna/probe for a space satellite. I think it launched on a Delta 4 rocket in June '02.
I like snow blowers better. /forums/images/graemlins/cool.gif
Good luck.
