ACMOC
Login
ACMOC
hyd cylinder direction why?

hyd cylinder direction why?

Showing 1 to 10 of 19 results
1
Jim Davis
Topic Author
Offline
Send a private message to Jim Davis
Posts: 480
Thank you received: 0
It seems to me that most hydraulic cylinders for blades are set up to lift the blade on retraction of the rod. I wonder why.

The retraction force is less than the extension force. Sometimes (digging out a stump or pushing over a tree) the more lifting force the better.

We had a holt blade with the cylinder mount geometry such that the cylinders lifted the blade on the extension stroke. My dad took out some big trees by getting under the root ball and lifting. My D2 with the opposite geometry could use some help in that regard, though nobody is going to rework the geometry.

Mostly just would like to understand the thinking of the engineers who designed the blade/hydraulic geometry.

Another observation, that Holt blade on the TD 6 would raise to about 3 feet off the ground, a big mechanical advantage over the 2-foot or so lift on my D2.

And yet another think issue, why are D2 and D4 blades set so far ahead of the hydraulic units? Looks to me like they could safely be at least 6 inches closer, reducing the infamous nose-heavy tendency.

Ready to read now...

Thanks

Jim
Please log in or create an account to join the conversation.
Thu, Jan 1, 2015 11:26 PM
neil
Offline
Moderator
Admin
Send a private message to neil
Posts: 6,962
Thank you received: 18
Hi Jim,
total guess on my part but for the ram direction, I pondered what the frame would look like if the ram extended to lift the blade, and it occurred to me that there would be a slightly more complex design and more steel in it. It seems to me that the D2 configuration is almost as simple as it can be.
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 1:30 AM
STEPHEN
Offline
Send a private message to STEPHEN
Posts: 2,461
Thank you received: 1
I think that in the early days at least, seal technology and system pressure was limited, so it would be better to have the larger piston area applying the digging forces, dozers do most of their work with the edge in the ground not the air.
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 1:35 AM
Jim Davis
Topic Author
Offline
Send a private message to Jim Davis
Posts: 480
Thank you received: 0
Reply to STEPHEN:
I think that in the early days at least, seal technology and system pressure was limited, so it would be better to have the larger piston area applying the digging forces, dozers do most of their work with the edge in the ground not the air.
Yes, but once a cylinder system is able to lift the front of the track frame, any greater down pressure force is irrelevant.

Hey, it works pretty well the way they did it, I just wonder about the thought process, part of which you have presented.

Thanks
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 1:40 AM
Jim Davis
Topic Author
Offline
Send a private message to Jim Davis
Posts: 480
Thank you received: 0
Reply to Jim Davis:
Yes, but once a cylinder system is able to lift the front of the track frame, any greater down pressure force is irrelevant.

Hey, it works pretty well the way they did it, I just wonder about the thought process, part of which you have presented.

Thanks
Here's a Holt blade on a D2. The original poster said the bottom the blade could be raised higher than the top of the radiator. No wonder I was remembering it coming way up (this was in the 1960s).
[attachment=26770]a66335.jpg[/attachment]

Back to the down pressure concept, cable blades do pretty well and the Holt setup would have more down pressure than a cable rig, right?
Attachment
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 2:06 AM
rjh-md
Offline
Send a private message to rjh-md
Posts: 394
Thank you received: 0
Reply to Jim Davis:
Yes, but once a cylinder system is able to lift the front of the track frame, any greater down pressure force is irrelevant.

Hey, it works pretty well the way they did it, I just wonder about the thought process, part of which you have presented.

Thanks
Using a d-2 or 4 for up routing trees with out a safey rops is a dangerous job .Its only going to take one hanging widow maker limb to come down on the operater to cause serious injury .Yrs ago I had a bad experience which I will never forget .Ihad a travel road threw the woods that at the time ,I used to track my 40A D-4 ,no canopy, throught the woods .One day I was going threw that woods ,and made a slight turning correction ,and the left side of the blade swung to the left and hit a tree on the side of the road ,and about 2 seconds later a 6 inch diamater about 10 ft long landed in my lap .The battery boxs on both sides saved me from the weight of the limb .My arms were pined though and could not throw the clutch out to stop the forward movement .I did manage to get my knee behind the clutch lever ,and throw it out . If that limb had landed 6" nearer me ,it would have hit me square in the head ,and I would not be writing this reply today !
Its the limb that you don't see is whats going to hurt or kill you .Its dangerous enough clearing with a tractor with a clearing rops because of spring back limbs that can make their way through the cab
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 2:21 AM
Sasquatch
Offline
Member
Send a private message to Sasquatch
Posts: 1,238
Thank you received: 1


Interesting you bring that up, it's something I never really thought about myself until seeing first hand the difference between the Cat 2A blade on my dad's D2 and the 2S blade on my D2. Since the 2A blade is intended to angle, of course then the center of the C frame will have to stand out farther in front of the hydraulic unit to permit the blade to achieve full angle and still have clearance in front of the tracks. Naturally, a down side of that situation is a blade that's a lot farther out in front of the tractor when it's set straight. Also, as a rule of thumb angle blades will always be wider than straight blades because when they're placed at their max. angle they still need to be just as wide as the machine (which I'm sure is already a well known fact here but since we're on the topic anyway), further compounding the nose heavy problem. For reference, take a look at the distance between the grill guard and the blade and C frame of the 2A setup in this picture-

[img]http://i802.photobucket.com/albums/yy310/TRNelson/photo23_zpsc17dae96.jpg[/img]


Then notice how the non adjustable 2S blade sits right in tight in front of the same grill guard on my D2 - this clearance looks about right to me, no wasted space, just enough to permit adequate travel without binding on anything.

[img]http://i802.photobucket.com/albums/yy310/TRNelson/photo22_zpsdca15b7d.jpg[/img]


But at the end of the day, a D2 is just so short that it'll always feel nose-heavy to some extent even with larger front idlers, although they do help. And as far as the hydraulic cylinder travel direction versus lifting/lowering, I think Stephen pretty much hit the nail on the head. A lot of the LaPlante/Choate blade mechanisms on the D2's also operated in reverse of the Cat units, like the one pictured below.

[img]http://i802.photobucket.com/albums/yy310/TRNelson/Cat%20D2/5UD22_zpsd4eca7c2.jpg[/img]
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 2:32 AM
Jim Davis
Topic Author
Offline
Send a private message to Jim Davis
Posts: 480
Thank you received: 0
Reply to rjh-md:
Using a d-2 or 4 for up routing trees with out a safey rops is a dangerous job .Its only going to take one hanging widow maker limb to come down on the operater to cause serious injury .Yrs ago I had a bad experience which I will never forget .Ihad a travel road threw the woods that at the time ,I used to track my 40A D-4 ,no canopy, throught the woods .One day I was going threw that woods ,and made a slight turning correction ,and the left side of the blade swung to the left and hit a tree on the side of the road ,and about 2 seconds later a 6 inch diamater about 10 ft long landed in my lap .The battery boxs on both sides saved me from the weight of the limb .My arms were pined though and could not throw the clutch out to stop the forward movement .I did manage to get my knee behind the clutch lever ,and throw it out . If that limb had landed 6" nearer me ,it would have hit me square in the head ,and I would not be writing this reply today !
Its the limb that you don't see is whats going to hurt or kill you .Its dangerous enough clearing with a tractor with a clearing rops because of spring back limbs that can make their way through the cab


Uh-huh. Have you been peeking at my D2?
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 3:19 AM
old-iron-habit
Offline
Member
Send a private message to old-iron-habit
Posts: 3,520
Thank you received: 0
Reply to Jim Davis:


Uh-huh. Have you been peeking at my D2?
If the cylinders are mounted in the opposite direction there is also more travel that the hoses need to have as the barrel of the cylinder moves with the blade. Probably easier to snag them with the bigger loop.
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 7:47 AM
Jim Davis
Topic Author
Offline
Send a private message to Jim Davis
Posts: 480
Thank you received: 0
Reply to old-iron-habit:
If the cylinders are mounted in the opposite direction there is also more travel that the hoses need to have as the barrel of the cylinder moves with the blade. Probably easier to snag them with the bigger loop.


This is not the case with the Holt and LaPlante/Choate shown above.
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 8:18 AM
drujinin
Offline
Send a private message to drujinin
Posts: 3,852
Thank you received: 1
Reply to old-iron-habit:
If the cylinders are mounted in the opposite direction there is also more travel that the hoses need to have as the barrel of the cylinder moves with the blade. Probably easier to snag them with the bigger loop.
The LaPlant setup Sasquatch has in the last photo will pick up the front of the Tracks when digging and will lift the rear of the Tractor when you have the blade hooked on a Root Ball.
Please log in or create an account to join the conversation.
Fri, Jan 2, 2015 8:31 AM
Showing 1 to 10 of 19 results
1
YouTube Video Placeholder

Follow Us on Social Media

Our channel highlights machines from the earliest Holt and Best track-type tractors, equipment from the start of Caterpillar in 1925, up to units built in the mid-1960s.

Upcoming Events

HAMILTON PASTURAL MUSEUM

Chapter Nineteen

| Cnr Hiller Lane and Ballarat Road, Hamilton, Vic, 3300

RUSSELL SAYWELL WORKING DAY

Chapter Two

| Pitt Farm, Little Paxton, St Neots, Cambridgeshire, PE19 6HD, UK

10th Annual Best of the West

Chapter Fifteen

| Historic Santa Margarita Ranch, 20000 El Camino Real, Santa Margarita, CA 93453, USA

ACMOC Chapter 30 - Celebrating 100 Years of Caterpillar

Chapter Thirty

| Hartley - South Australia
View Calendar
ACMOC

Antique Caterpillar
Machinery Owners Club

1115 Madison St NE # 1117
Salem, OR 97301

[email protected]

Terms & Privacy
Website developed by AdCo

Testimonials

"I became a member recently because the wealth of knowledge here is priceless." 
-Chris R

Join Today!