Thursday, August 14, 2014

Hydraulic Cylinders and Excavators and Old Cable Shovels

(Update: pictures of big excavators now that hydraulics have become good enough to completely replace friction drum equipment. Science Channel Impossible Engineering, S3 E4, Ice Base @ 39:28: In 1795, Joseph Bramah invented the hand pump and hydraulic ram to create a press.)

Hydraulic cylinder seems to be the correct term for what I know of as a hydraulic ram. It is a linear actuator that revolutionized the design of farm and construction equipment.

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Update: a video about hydraulics.

Above is the ram for the boom-stick joint at the top of the Deere excavator in the following photo.


The chrome-plated steel piston rod passes through a seal gland in the cylinder head. The following diagram illustrates that the piston rod (red) connects to a piston (orange).


The two blue rectangles indicate ports where hydraulic hoses would attach. Both single-acting and double-acting rams have the dark blue connection. When a valve opens and allows fluid to flow from the hydraulic pump to the dark blue port, the piston rod is shoved out of the cylinder or extended. For a double-acting cylinder, which would also have a hose connected to the the light-blue port, the value would have to connect that hose to the hydraulic reservoir to allow fluid to drain out of the head port while fluid is entering the base or cap port. When the valve connects the head port to the pump and the cap port to the reservoir, the piston rod is pulled in or retracted. (A single-action ram can't force the rod to be retracted.)

The first front loader my Grandpa got for his Ford tractor had single-acting rams. The valve connected the port at the bottom to the pump supply to raise the loader. To lower it, the valve connected the port to the reservoir, and the loader was forced down by gravity. Note that a single-action cylinder does not need a seal gland because there is no oil on the head side of the piston. But now that manufactures have developed the machine tools necessary to build seal glands they are economic enough that the only rams I have seen the last few decades are double-acting.


When I was a kid in the 1960s, the excavators that I watched work had friction drums and cables instead of hydraulics.
http://en.wikipedia.org/wiki/File:Old_excavator.jpg

I believe I was seeing backhoes on a tractor in the 1960s. These had a power shovel mounted on the back of a tractor and a loader on the front.
20140811 0469

But it took longer for hydraulic technology to advance enough to handle the horsepower of an excavator. In an excavator, all of the horsepower of the diesel engine is used by just hydraulic pumps. Even the tracks are run by hydraulic motors. According to Wikipeida, the engine would drive a couple of high-pressure (up to 5000 psi) pumps for the actuators and a lower pressure pump (700 psi) to control the actuator valves so that the operator valves required less effort to operate. Hydraulic technology has advanced enough that even huge mining shovels have converted from cable to hydraulic cylinders. The current largest hydraulic excavator is the 4500 hp CAT 6090. A video of the CAT 6060 provides a better explanation of these beasts.

My father-in-law worked for a company that built drilling rigs on trucks. I remember him telling about converting the rigs from cables to hydraulic cylinders. They started having field support problems because the hydraulic force was so powerful it was bending the boom. They had to completely redesign the unit to work properly with hydraulics.

The top and bottom cables each have their own winch. When the operator pulls back on the control for the top cable so that the cable is reeled in, it is rather obvious that the boom will go up. And if the bottom cable is reeled in, the bucket will go towards the operator. What is not so obvious to me is that when the bottom cable is reeled in, the boom also goes up. If the operator wants the bucket to dig a flat trench, he needs to reel out the top cable as the bottom cable is reeled in. You can watch a video of this shovel and another in operation.

Anders Eriksson posted
Ruston-Bucyrus 19-RB at a vintage machinery meeting in Sweden last summer.

Chuck Seelen posted, cropped
Garret Wilson That's beautiful, I'm a huge fan of those PL undercarriages too!

Ben Stalvey posted
So for those asking if Manitowoc made cable backhoe versions. Here is one several models were used for them. 3000. 3500s, 3900 even 4600s.
John Fraser Backhoe or Back-actor on a friction clutch and brake machine could be a difficult piece of equipment, depending on the terrain. I have used it a few times and it was a particular challenge when excavating blasted rock.
John Suckoe 3900 max 4600 on barge

John W. Coke posted two photos.
1

2

Screenshot, found the post. Zagray museum May 4, 2019, Connecticut
I don't like profile videos, especially of horizontal subjects, but this was a better vantage point.
Screenshot

Historische Baumaschinen posted
Expedition to the Animal Kingdom: The Priestman Program 1968
Daniel Krähenbühl shared

Gladowski posted a Facebook reel

Paul Mandra commented on Mike Gladowski's post

Bradley Haines posted video and photos of both backhoe and face shovels.

1 of 4 photos posted by Missouri's Historic Highways
07-24-1953 Rt. 65, South Cry Sac Creek Greene County
Dennis DeBruler: Thanks. I have been looking for years for a photo of an excavator before hydraulic controls were developed.
 
Leo Odijk posted
Koehring dieplepel.
Daniel Krähenbühl shared

Backhoes were not developed until the 20th Century. But steam-driven face shoves were developed in the 19th Century. Cable driven face shovels grew really big because they were used for strip mining. The Captain (Marion 6360) is an example of a more modern large shovel. In fact, large face shovels are still made with cables, but I can't find my notes on that.

Screenshot @ -3:50
This rail mounted steam shovel is believed to be the only working example of it's type in the World.
It was recovered in 1977 by Ray Hooley from a chalk pit in Arlesey, County Bedfordshire which supplied a cement works. It was used as a face shovel and was one of two that worked the quarry until the 1920s.
Two examples of this machine worked the quarry and both were abandoned when the pit closed in the 1930's. during WW2 the shovel on the upper level was recovered for scrap but the one on the lower level was abandoned due to being submerged and hard to reach.
After recovery in 1977, the steam shovel was restored at Ruston's Lincoln works by 1980, and was given on permanent loan to the museum of Lincolnshire life. By 2008 after the machine falling into disrepair, Ray Hooley gave the shovel to the Vintage excavator trust located at Threlkeld quarry in Cumbria who have restored it to it's former glory with the assistance of a National lottery.

Screenshot @ -3:59

I didn't know they made face shovels this small by the time they quit using steam. I'm used to seeing mining shovels being quit large.
Barry Thornberry posted


Ben Stalvey posted
Nothing like a old Manitowoc Speed shovel
Robert MacKenna Beautiful 3000
Jackie Mensch Never ran a Manitowoc. B&E
Jesus Cortes Manzanares posted
Cananea sonora México
[This shows that the cranes used steam power well after the development of the internal combustion engine. Note only is the truck small for mining, it has no cab!]

This is like the cable excavators I remember seeing when I was a kid in the 1950s. The bucket is rigid. To unload it, the boom has to be raised by pulling on the upper cable and the stick extended by reeling out the lower cable.


Barry Thornberry posted
[The old and the older. Big Brutus "The world's biggest electric shovel." I didn't even know there was strip mining in Kansas.]

Update:
Andre Tardif shared
[Note the skid loader under the regular sized excavator.]

And excavators kept growing.
Screenshot
This machine is called CAT 6015B and it is the largest of its kind standing at over 70m (230') tall

Some photos of plowing with a moldboard plow show how a lever was used to raise the plow at the headland before hydraulic circuits were added to tractors.

Kirby Lamp posted
Dennis DeBruler I was surprised that an old-looking loader has double-acting hydraulic rams. I remember my grandfather's first loader had just a single acting ram because creating a seal around the ram to apply downward pressure had not been perfected. And because gravity did a good job of lowering the loader.Kirby Lamp grandpa had that loader on a m that i have now never have taken all the bracket of the tractor for some reason.
[The "m" would have been a Farmall M tractor.]
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safe_image for A Shifting Fluid Power Industry
"The transition to electrification will bring about a need to rethink the design of traditional hydraulic systems."
[They replace hydraulic fluid with a belt on a pulley system in the cylinder. The belt is driven directly by an electronically controlled motor. And the motor can act as a generator when a load is lowered. And the article says that hydraulic cylinders can't pull as well as they can push, but their new cylinder design can do both with equal strength. They don't mention it, but it seems that stringing wires rather than hoses around a machine would reduce maintenance issues. Wires generally don't have a problem with leaks.]



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