Front loader for a B7200

[Paul Allwood]

Today I got the loader sub-frame bolted in place. Still planning to add a brace across the top between the two towers - need to sit and look at it for a bit to work out what I'm going to do first. Next I'll start on the loader arms, then the bucket and hydraulics.

 

[jaxs]

Nice work Paul, m-i-t-t-y nice.

 

[Paul Allwood]

Nice work Paul, m-i-t-t-y nice.

Thanks mate

 

[torch]

Today I got the loader sub-frame bolted in place. Still planning to add a brace across the top between the two towers - need to sit and look at it for a bit to work out what I'm going to do first. Next I'll start on the loader arms, then the bucket and hydraulics.

Very nice work!

I'm not sure bracing the tops of the towers is necessary -- you have them very well braced at the bottom. They do look a bit short to my eye though. Is that the planned height or is there more to come? I'm not sure what your planned bucket dump height is but remember that a taller tower helps keep the bucket forward of the tractor at a given height. You don't want to be dumping the load onto the hood!

When I designed mine, I did a LOT of scale sketches, similar to this, to work out the geometry. I ended up with the pivot point of the loader arms about 6" above the hood height. Different tractor of course, but similar in scale.

 

[Russell King]

One other thing to consider is to give yourself something that helps you get onto the tractor (besides the steering wheel). That may not be a problem now, but as age happens you may find that step up distance grows at an exponential rate as balance decreases in a linear fashion!

It looks good!

 

[Paul Allwood]

Very nice work!

I'm not sure bracing the tops of the towers is necessary -- you have them very well braced at the bottom. They do look a bit short to my eye though. Is that the planned height or is there more to come? I'm not sure what your planned bucket dump height is but remember that a taller tower helps keep the bucket forward of the tractor at a given height. You don't want to be dumping the load onto the hood!

When I designed mine, I did a LOT of scale sketches, similar to this, to work out the geometry. I ended up with the pivot point of the loader arms about 6" above the hood height. Different tractor of course, but similar in scale.

There is more to come. What you can see so far is the support frame that stays attached to the tractor. There are posts that fit into the towers that will allow me to fit and remove the loader, hopefully reasonably easily. I've attached an earlier pic that shows the removable uprights fitted into the towers.

Thanks for the comments on the height and your drawings - really appreciated. I'll keep that in mind when I build the loader arms - so far I only have them prototyped in plywood.

 

[Paul Allwood]

One other thing to consider is to give yourself something that helps you get onto the tractor (besides the steering wheel). That may not be a problem now, but as age happens you may find that step up distance grows at an exponential rate as balance decreases in a linear fashion!

It looks good!

Thanks - I like your description of aging.

 

[Paul Allwood]

A bit more progress on the loader over the last few days, mostly on the arms.

It doesn't seem to matter how hard I try to make things "not too heavy", they always seem to end up heavy. For the arms I've used mostly 100x50x4 mm RHS.

I've used 2" bore x 10" stroke cylinders for the lift and positioned them so that if I pump the same amount of oil they will do roughly the same job as the 1.5" bore x 16" stroke cylinders that seem to be common. Why ? Because I could get the cylinders I'm using for about a third the price locally.

The single tilt cylinder is a copy of the LA344 (maybe others ?) design with the same cylinder specs - 2.5" bore x 8" stroke. I was looking at all sorts of options but gave up, figuring if it works for Kubota it will probably work for me.

You'll see in one of the pics I even had the quality inspector on the job.

 

[torch]

I've used 2" bore x 10" stroke cylinders for the lift and positioned them so that if I pump the same amount of oil they will do roughly the same job as the 1.5" bore x 16" stroke cylinders that seem to be common. Why ? Because I could get the cylinders I'm using for about a third the price locally.

Very nice.

I also bought 2" diameter cylinders because they were on sale when I built mine. However, I bought 16" stroke ones. I think your approach may be better -- mine is capable of lifting more weight than I really should with a B7100. I knew that going in, but thought I could simply reduce the relief valve setting to limit the load on the front axle. I didn't clue in that it would also reduce the pressure available to the 3PH cylinder and I had to put it back. Also, the cycle time increases with increased volume, so filling 16" cylinders will take longer than filling 10" cylinders. I upgraded the pump to a higher volume unit to compensate but yours should be equivalent without that added expense.

The only concern I have is that your geometry necessarily moves the mounting point of the cylinder closer to the tower, so there is more arm beyond the cylinder mount, and therefore more bending force on the arm.

 

[TheOldHokie]

Very nice.

I also bought 2" diameter cylinders because they were on sale when I built mine. However, I bought 16" stroke ones. I think your approach may be better -- mine is capable of lifting more weight than I really should with a B7100. I knew that going in, but thought I could simply reduce the relief valve setting to limit the load on the front axle. I didn't clue in that it would also reduce the pressure available to the 3PH cylinder and I had to put it back. Also, the cycle time increases with increased volume, so filling 16" cylinders will take longer than filling 10" cylinders. I upgraded the pump to a higher volume unit to compensate but yours should be equivalent without that added expense.

The only concern I have is that your geometry necessarily moves the mounting point of the cylinder closer to the tower, so there is more arm beyond the cylinder mount, and therefore more bending force on the arm.

He builds pretty stout so bending is probably not a concern. My thoughts were more bounce and harder to control. He will know more once he has it hooked to the valve...

Dan

PS > Port reliefs will reduce your boom lift without affecting the downstream valves.

 

[Paul Allwood]

Very nice.

I also bought 2" diameter cylinders because they were on sale when I built mine. However, I bought 16" stroke ones. I think your approach may be better -- mine is capable of lifting more weight than I really should with a B7100. I knew that going in, but thought I could simply reduce the relief valve setting to limit the load on the front axle. I didn't clue in that it would also reduce the pressure available to the 3PH cylinder and I had to put it back. Also, the cycle time increases with increased volume, so filling 16" cylinders will take longer than filling 10" cylinders. I upgraded the pump to a higher volume unit to compensate but yours should be equivalent without that added expense.

The only concern I have is that your geometry necessarily moves the mounting point of the cylinder closer to the tower, so there is more arm beyond the cylinder mount, and therefore more bending force on the arm.

Thanks for the comments. You're right about the location of the bending force on the arms. Hopefully I've reinforced it enough - I guess I'll find out if I haven't.

 

[TheOldHokie]

Thanks for the comments. You're right about the location of the bending force on the arms. Hopefully I've reinforced it enough - I guess I'll find out if I haven't.

IIRC a B1630 was rated fof ~500#. Unless you are going more than that I think you are more than safe.

I wish I had your welding skills

Dan

 

[Paul Allwood]

He builds pretty stout so bending is probably not a concern. My thoughts were more bounce and harder to control. He will know more once he has it hooked to the valve...

Dan

PS > Port reliefs will reduce your boom lift without affecting the downstream valves.

I've never used or built one so I'm interested in what would contribute to bounce and being hard to control ?

Also, what are port reliefs ?

 

[Paul Allwood]

IIRC a B1630 was rated fof ~500#. Unless you are going more than that I think you are more than safe.

I wish I had your welding skills

Dan

Thanks Dan. Some of the welds look ok, from a distance. Even better with a coat of paint.

 

[TheOldHokie]

I've never used or built one so I'm interested in what would contribute to bounce and being hard to control ?

Also, what are port reliefs ?

Bounce from the longer lever arm acting on the tractor.

Twitchier controls from the shorter lever arm acting on the boom.

A port relief is a relief valve between the workport on the valve and the cylinder. It can reduce higher pressure coming from the valve without reducing carry over pressure. Since all you are worried about is lifting power you only need it on the lift side of the circuit.

Do you have a valve picked out?

Dan

 

[Paul Allwood]

Bounce from the longer lever arm acting on the tractor.

Twitchier controls from the shorter lever arm acting on the boom.

A port relief is a relief valve between the workport on the valve and the cylinder. It can reduce higher pressure coming from the valve without reducing carry over pressure. Since all you are worried about is lifting power you only need it on the lift side of the circuit.

Do you have a valve picked out?

Dan

Ok, thanks again.

I do have a valve - 3 spool with float on the raise/lower spool. The 3rd spool is to allow for a 4 in 1 bucket or a grapple down the track, but I'll make a basic bucket first.

 

[torch]

Also, what are port reliefs ?

I think the port relief comment was aimed at me -- a way to limit the lifting force on my loader without affecting the pressure available to the 3PH.

 

[Paul Allwood]

I think the port relief comment was aimed at me -- a way to limit the lifting force on my loader without affecting the pressure available to the 3PH.

Yeah, all good. I was interested too as I'm new to this stuff and have a lot to learn.

 

[Paul Allwood]

I'm hoping someone can help with some dimensions. My plan is to fabricate a standard SSQA attachment receiver for the front of the loader. I've seen a few drawings that show widths clearly enough, but I'm struggling to find anything that isn't too blurry to read that would give dimensions 'A' and 'B' shown on my attached sketch of a section view of an attachment plate.

Can anyone point to a readable drawing ?

Many thanks, and apologies if it's right in front of me and I can't see it. Apparently it's a special skill of mine

 

[chim]

I have three that I measured this morning. Dimension "A" is 16" and Dimension "B" is 1-1/2".

For the first project that required a plate (snow plow) the first plate had to be returned because it was just a bit short in the "A" dimension and the tabs on the Kubota's loader were longer than that. When the top of the plate was hooked on the Kubota, the bottom was held away by the bottom tabs of the plate and the round pins couldn't engage. The manufacturer (I think it was Titan, but sold through a third party) paid the shipping.

Also, the square holes in the bottom are cut square with the material, rather than parallel with the plate so that the flat part of the round pin
makes full contact.

One is a 3/8" thick plate and another is a square tube frame - both already made up that I purchased. The third is a square tube frame I made for a recent project.

Pics below are from the (purchased) snow plow plate. The 16" is with the end of my folding rule jammed into the upper bend. Sorry for the out-of-focus shot