Post by Ronmar on Sept 19, 2010 23:14:11 GMT -5
I have been sick all weekend and just setting around going stir crazy so I thought I would document how to tighten up the joystick on a Chinese BH. This may also apply to a Chinese loader control valve.
The problem: The first illustration ABOVE is a top view of the joystick pivot assembly. The use of a regular free pin at position B with cotter-pin retainer is the main issue. Because of the thin material and hole tolerances, that pin is free to slop around a bit which allows the whole “O” frame(in red) to wobble around inside the yolk(green) which is bolted over the spool valve I. This is the same problem the main BH boom pivots suffer from, well that is the problem mine used to suffer from:)...
As you go to push the joystick forward, you must first take up all this slack at B, before lever E can push down on the spool valve I. Same goes for a side to side motion, the slop at pin B must be taken up before the lever on the side of the "O" frame (F) even starts to move spool G up or down. Pin C is a screw in affair that when tight becomes a rigid pivot point on the “O” frame. This is what is needed at pin B, so this is what I did. I initially thought of tapping the hole for a screw-in pin at B, but then I came up with an easier solution.
The second drawing BELOW shows pin B reversed and pushed in from the “O” frame side. I welded the head of this pin to the inside of the “O” frame, welds shown in blue.
Here is how you do it:
Disassemble the joystick by removing the cotter pin and pin A. Tilt and lift the joystick block clear of the “O” frame. I unscrew the joystick lever before I do this. Remove the cotter pin and pin B and unscrew pivot pin C and lift the “O” frame clear of the yolk.
Slide pin B into it’s hole from the inside of the “O” frame and weld the head in place to the inside wall of the “O” frame main hole. Depending on the size of your lever block E, and the size of your pin head, you may or may not need to use a die grinder to shave the top of the pin head and welds down a bit so the lever block can be inserted. Shorten pin B by grinding off the other end of the pin down till you just remove the cotter pin hole. This is easier after welded into the “O” frame:) You have to shorten this pin to allow it to be slid back into the yolk hole while simultaneously inserting the “O” frame lever arm F back into spool G. Once you have pin B shortened enough to allow assembly, loosely assemble it into the yolk and note the gaps between “O” frame and yolk when lever F is centered in spool G. Find some flat washers to fill these gaps(shown in dark grey). And re-assemble using lock-tight on pin C’s threads.
Since pin A is supported on both sides by the “O” frame, it is a good pivot for block E. It just needs some washers to take up most of the side to side slop between the block and the inside of the "O" frame . You want most all the gap taken up at the pivots by washers, but you need to leave a little room for ease of movement. To tight and the assembly will start to bind as you move the joystick out to the corners of it's travel. Once the lever block E is re-installed with it’s side washers, put a drop or two of lube down the threaded hole(I use gear oil) to lube the pin where it passes thru the block, and re-install the joystick handle. I also used lock-tight here, and at the threads on lever F where it screws into the side of the “O” frame. Lube pins B and C where they pass thru the yolk and the ball ends of the levers where they are inserted into the spool valves.
It took me way longer to write this than it actually takes to do it, and the joystick control is now much more precise.
Enjoy...
The problem: The first illustration ABOVE is a top view of the joystick pivot assembly. The use of a regular free pin at position B with cotter-pin retainer is the main issue. Because of the thin material and hole tolerances, that pin is free to slop around a bit which allows the whole “O” frame(in red) to wobble around inside the yolk(green) which is bolted over the spool valve I. This is the same problem the main BH boom pivots suffer from, well that is the problem mine used to suffer from:)...
As you go to push the joystick forward, you must first take up all this slack at B, before lever E can push down on the spool valve I. Same goes for a side to side motion, the slop at pin B must be taken up before the lever on the side of the "O" frame (F) even starts to move spool G up or down. Pin C is a screw in affair that when tight becomes a rigid pivot point on the “O” frame. This is what is needed at pin B, so this is what I did. I initially thought of tapping the hole for a screw-in pin at B, but then I came up with an easier solution.
The second drawing BELOW shows pin B reversed and pushed in from the “O” frame side. I welded the head of this pin to the inside of the “O” frame, welds shown in blue.
Here is how you do it:
Disassemble the joystick by removing the cotter pin and pin A. Tilt and lift the joystick block clear of the “O” frame. I unscrew the joystick lever before I do this. Remove the cotter pin and pin B and unscrew pivot pin C and lift the “O” frame clear of the yolk.
Slide pin B into it’s hole from the inside of the “O” frame and weld the head in place to the inside wall of the “O” frame main hole. Depending on the size of your lever block E, and the size of your pin head, you may or may not need to use a die grinder to shave the top of the pin head and welds down a bit so the lever block can be inserted. Shorten pin B by grinding off the other end of the pin down till you just remove the cotter pin hole. This is easier after welded into the “O” frame:) You have to shorten this pin to allow it to be slid back into the yolk hole while simultaneously inserting the “O” frame lever arm F back into spool G. Once you have pin B shortened enough to allow assembly, loosely assemble it into the yolk and note the gaps between “O” frame and yolk when lever F is centered in spool G. Find some flat washers to fill these gaps(shown in dark grey). And re-assemble using lock-tight on pin C’s threads.
Since pin A is supported on both sides by the “O” frame, it is a good pivot for block E. It just needs some washers to take up most of the side to side slop between the block and the inside of the "O" frame . You want most all the gap taken up at the pivots by washers, but you need to leave a little room for ease of movement. To tight and the assembly will start to bind as you move the joystick out to the corners of it's travel. Once the lever block E is re-installed with it’s side washers, put a drop or two of lube down the threaded hole(I use gear oil) to lube the pin where it passes thru the block, and re-install the joystick handle. I also used lock-tight here, and at the threads on lever F where it screws into the side of the “O” frame. Lube pins B and C where they pass thru the yolk and the ball ends of the levers where they are inserted into the spool valves.
It took me way longer to write this than it actually takes to do it, and the joystick control is now much more precise.
Enjoy...
