• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

The Great Gradall Project

245dlc

Senior Member
Joined
Mar 16, 2010
Messages
1,228
Location
Canada
Occupation
Heavy Equipment Operator
Certainly an interesting project. I recently saw a G3WD for sale and somebody had switched the excavator controls to the typical Caterpillar pattern that you have on conventional machines. Something I would probably do if I decided to buy one.
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
Certainly an interesting project. I recently saw a G3WD for sale and somebody had switched the excavator controls to the typical Caterpillar pattern that you have on conventional machines. Something I would probably do if I decided to buy one.

I want to try out the Gradall pattern first, but yeah, I've definitely considered this. Should be as simple as swapping a few pilot lines.

Update on the steering box:

The hole in the center of the previously posted picture is supposed to be open. It gives you an obvious indication that the inner seal is blown by pissing fluid everywhere. Guess it works... :rolleyes: We are going to see if we can get the seals and replace them ourselves, but many steering box companies will only sell rebuilt kits to certified rebuilders. I guess that makes sense. Either way, we'll be taking car of that this week.

Moving a truck with no power or brakes is ok, but boy oh boy....its a different animal altogether when the steering is disconnected too! Imagine one of those screwed up shopping carts at Wal-Mart except it weighs 20 tons and you've got to move it down a slight hill and park it between two other trucks. We got her parked, though!
 

245dlc

Senior Member
Joined
Mar 16, 2010
Messages
1,228
Location
Canada
Occupation
Heavy Equipment Operator
Lol good thing you have a loader to move it around with.
 

kshansen

Senior Member
Joined
Mar 11, 2012
Messages
11,128
Location
Central New York, USA
Occupation
Retired Mechanic in Stone Quarry
I want to try out the Gradall pattern first, but yeah, I've definitely considered this. Should be as simple as swapping a few pilot lines.

Update on the steering box:

The hole in the center of the previously posted picture is supposed to be open. It gives you an obvious indication that the inner seal is blown by pissing fluid everywhere. Guess it works... :rolleyes:

I think I'd plug it with a plastic "cap plug" plug or cork to keep dirt out. If it does start leaking enough to cause a problem the cap plug or cork will fall out.
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
I think I'd plug it with a plastic "cap plug" plug or cork to keep dirt out. If it does start leaking enough to cause a problem the cap plug or cork will fall out.

That's how it is originally designed, with just a vent plug in there to keep debris out. Its not even threaded. However, the fact that it popped out and is pissing oil indicates that the main sector shaft seal is blown.

The area that hole goes into is normally on the dry side of the seal. If its wet back there, its time for a rebuild!
 

kshansen

Senior Member
Joined
Mar 11, 2012
Messages
11,128
Location
Central New York, USA
Occupation
Retired Mechanic in Stone Quarry
That's how it is originally designed, with just a vent plug in there to keep debris out. Its not even threaded. However, the fact that it popped out and is pissing oil indicates that the main sector shaft seal is blown.

The area that hole goes into is normally on the dry side of the seal. If its wet back there, its time for a rebuild!

I know I have seen many hydraulic pump that are driven by say a converter or engine gear train that have seals to keep pump oil in pump and another to keep drive unit oil in the drive and they use a plastic plug in a drilled passage between the two seals on the "dry sides" and when there is a leak the leak pushes the plug out then you see the leak!
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
The local truck parts distributor told us that the rebuild kit for this box is no longer manufactured and they were unable to locate one. Gradall had one in stock, but we got the LAST one. Guess that means we better get this rebuild right.

I located the rebuild manual and disassembly went smoothly (always does, right?).

IMAG2272.jpg

At this point we discovered that the sector shaft bushing opposite the pittman arm was complete whupped (over 0.010" play) in the vertical direction. This seemed to indicate that there was too much pre-load in the sector shaft likely due to an over-zealous adjustment. This bushing was also where the failed seal was, so this excessive wear likely caused the seal failure. We were able to locate a replacement bushing on Mcmaster but that means the box won't be finished until next week. The overload in the gear mesh was apparent when we went to replace the end cover and found that the sector shaft wanted to bite into the lower lip of the bushing and simply would NOT be made to go straight. Based on this, we decided it would be prudent to replace the bearing that supports the other end of the sector shaft because it was probably working too hard as well. However, it looks like this needle bearing is an usual size.....so that means another wild goose chase. :rolleyes:

IMAG2273.jpg

The low carrier mileage (4500) means that the overloaded gear mesh didn't have too much time to damage the main piston bore.

IMAG2277.jpg

In the next post, I'll talk a bit about the seal installation.
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
Most of the seals on this box consisted of thin, square Teflon rings with backing O-rings. The Teflon rings stretch during installation (soaking in hot water helps) and need to be compressed afterwards to fit into their bores without tearing. This requires special tools that we were unable to locate (looked like tapered plastic sleeves). However, one of our guys mentioned that at their cylinder shop they usually just used hose clamps with business cards acting as shims. We tried it....and it worked!

O-rings everywhere...

IMAG2275.jpg

When this seal finally made it down the shaft, it was stretched to the point where it would completely come out of the seating groove when the "slack" was pushed to one spot. This is a picture of what it looked like after the hose clamp was tightened (which gathered the slack in the seal to right under the clamp screw, the one spot without uniform compression). With a little squeezing with some channel-locks, it sat right down.

IMAG2276.jpg

The same process worked with the bigger seals on the valve sleeve:

IMAG2280.jpg

Everything fit together fine with liberal lubrication:

IMAG2278.jpg

By the end of the day, the main piston/worm gear was rebuilt and reinstalled, including input shaft seals. Just need to get the bearing and bushing in this week and we should have this box back on the machine in nearly-new condition!

IMAG2282.jpg
 

BobCatBob

Senior Member
Joined
Mar 4, 2010
Messages
296
Location
Chicago
Nice work ! I've used playing cards with transmission assembly goo in a similar situation.
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
I've gotten a bit behind in the updates....here they are!

I left off where we had finished the steering box rebuild up until the point where the bearing and bushing that support the ends of the sector shaft needed to be replaced. The bushing was available on McMaster (steel-backed teflon coated sleeve bearing) but over twice as long as needed. These sleeve bearings are split at one point, and we were afraid of that split catching on a standard lathe tool bit and destroying the bearing. Pat's dad suggested we turn it on a lathe but use a Dremel as the cutting tool. We did that at a robotics meeting, and it worked like a charm.

The bearing ended up being a special order. As soon as I told the sales rep for Eastern Industrial that it was for a steering box, he told me that anytime he gets a bearing request for a steering box, its a weird size. Turns out this one was no different. Wallet was a bit thin after that one...

Armed with both bearings, we got back into the rebuild:

IMAG2315.jpg

This weekend was quite interesting, as I was sharing the bay with a 70 ton Grove crane that had been hydro-locked.

IMAG2316.jpg

The needle bearing was an odd size that was thinner than most. Not much meat to the outer race, and no inner race. To minimize the press force required, we chilled the bearing in a freezer (on the coils) and heated the box casting until it was almost impossible to touch. Bearing pressed in with very minimal force.

IMAG2317.jpg

The bolts holding the sector shaft cover in required torquing to over 200 ft-lbs. Pat had to bring out the BIG torque wrench.

IMAG2318.jpg

Here is your's truly performing the final benchtop tests to set the pre-load and backlash. The final numbers for input-shaft torque were right in the range suggested in the manual, meaning we probably didn't screw it up!

EDIT: While performing this procedure, I figured out that it was VERY easy to set the pre-load on the gear mesh and then torque the lock nut without realizing you had ALSO spun the pre-load adjustment screw enough to triple the pre-load. This probably explained why the original box had failed after only 4500 miles....the wear on the sleeve bearing was consistent with enormous pre-load on the gear mesh.

If the original assembler forgot to check the input-shaft toque again after setting the lock nut.....it could have left the factory with a destructive amount of mesh pre-load.

Moral of the story.....always double-check critical measurements!!

IMG_1036_2.jpg
 
Last edited:

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
Hey guys! Sorry about the delay...

I do have some pictures of work that happened just after this that I will post. Unfortunately most of the time since hasn't involved forward progress due to two more urgent projects that came up:

The first was a local theater that myself and Pat are assistant technical directors for. The building is owned by the town and some major structural renovations were required over the stage. This meant we had to remove the entire production package and re-install it after the work was done. Based on my rigging background, I ended up as the lead rigger. It was an awful lot of fun with traditional block and tackle type rigging work, but ate up most of my weekends for a couple months....especially since I was one of the few guys who was willing to throw on a harness and work 30' over the stage.

The second project, just after that, involved a major overhaul of a Bridgeport machine in the shop our robotics team uses. It needed some major cleaning and re-work, including a new gib (tapered wedge that adjusts the tightness of the table). These gibs are fitted by hand...by scraping away the high spots a few ten-thousandths at a time using special bluing dyes and techniques. That was a HUGE learning curve...but we're nearly done with it.

We hope to be back into this old Gradall soon!
 

oregon96pd

Well-Known Member
Joined
Mar 14, 2009
Messages
173
Location
Milton Freewater, OR
Removing the Pittman arm took a few tries, but we ended up just placing a chisel into the gap where the clamp bolt was and driving it in until it bit. With a few more blows....she slid right off.

View attachment 117496

Be very careful doing this. When I was 18 and just starting out as a mechanic I did that on a log truck, after I drove the chisel in I leaned over to get my pry bar. As I was standin back up the chisel shot out, bounced off the power steering reservoir and hit me square in the upper lip. The hole in my lip heeled but the missing chip of my tooth by the gum line never has :Banghead
 

CraneInnovation

Well-Known Member
Joined
Jul 24, 2013
Messages
143
Location
United States
Occupation
Structural Engineer
just wondering how this project was going is it all completed and painted up ?

Its been on hold due to life....but we are resurrecting it. Had an electrical design meeting tonight and we are forging the new schematic.

Been a year or so.....had our first little girl. I can't wait to get her out turning wrenches and working with daddy.

IMG_20160924_114902176.jpg

Hope to get this thread off the ground again and get this old Gradall back into service.
 

BobCatBob

Senior Member
Joined
Mar 4, 2010
Messages
296
Location
Chicago
Nice work! She'll be watching "Bob the builder" and "Handy Mandy" in no time. Then she'll be discussing torque values for grade 5 vs. 8 bolts. Looking forward to updates on the Grade All. I'm almost done with the Galion....but with a child myself, family 1st.
 

td25c

Senior Member
Joined
Feb 14, 2009
Messages
5,250
Location
indiana
Its been on hold due to life....but we are resurrecting it. Had an electrical design meeting tonight and we are forging the new schematic.

Been a year or so.....had our first little girl. I can't wait to get her out turning wrenches and working with daddy.

View attachment 160742

Hope to get this thread off the ground again and get this old Gradall back into service.

Nice work CraneInnovation !

I was talking about the new addition to the family .:thumbsup


Hey ....... The Gradall G3WD looks good to .:D;)
 
Top