Crawling on the shoulders of giants

16 December 2011

Last month, Stuart Anderson explained how alternative lifting devices built by heavy lift specialists have come to share more and more with crawler cranes. This month, he considers the troubled state of the mainstream crawler industry, the development of crawlers from 100t in 1947 to 3,200t today.

As with most other sectors, demand for new crawler cranes is going through a pretty tough time right now. Customer confidence has taken a real beating in 2011. When considering major capital goods purchases—such as big cranes—confidence is king. A few months ago it appeared that demand for larger-sized crawlers would provide the industry with some real offset for slowing mainstream demand. But then the Fukushima accident and the knee-jerk reaction it provoked led politicians to pause nuclear-related decisions—and with it decisions on the super-sized crawler cranes needed to build them.

In time, hopefully shortly, the work to properly protect or decommission all of the old nuclear plants will provide a whole lot of crane work.And hopefully the politicians will soon recognise that delaying new nuclear is not an option.

It had also seemed that demand in China and India would stay strong. But as I saw during my recent tour of China’s major crane plants there is no immunity. “Demand for construction machinery has shrunk drastically and growth will no doubt continue to slow next year”, announced Zoomlion chairman and CEO Zhan Chunxin on the 15th November.

He added that China’s demand for cranes and excavators will continue to slow next year because of waning economic growth and cutbacks in railway building in China. This announcement came just weeks after only the second 1,000t Zoomlion crawler thus far built suffered a catastrophic boom failure killing five people on a domestic wind farm project.

The end of an era
And just to finish with the bad news, these hard times are hurting a lot of good people in all areas of the crane business. There have been widespread lay-offs, but so far only one plant closure; that of Terex Wilmington. This is a sad, but probably inevitable event.

When Terex bought American Crane in 1997 several other potential acquirers had looked and walked away. Since its many decades of true glory based in St Paul, Minnesota, the former American Hoist & Derrick Company, known as “the Hoist”, had fallen far.

With such a massive infrastructure and skill-base vested in traditional mechanical cranes, the transition to hydraulics almost killed the company. Its roll of the dice in 1985, moving to the lower “Southern” manufacturing costs of Wilmington, North Carolina, effectively jettisoned its Northern skill base. Nevertheless it survived, barely, until Terex (and critically Fil Filipov) added the business to its fast-growing portfolio.

The key to the turnaround was the deal struck in 1998 with Japan’s IHI, with whom Terex subsidiary Koehring had an excavator/crane OEM supply relationship going back 35 years. A tough and ambitious deal was negotiated, and the result has been the sale of some 700 Terex-American cranes made by IHI that customers have come to regard as ‘bullet-proof’.

These cranes employed booms previously designed by American Hoist and manufactured in Wilmington. But in reality today, few customers buy these Terex-American cranes because of the ‘lure’ of their domestically made booms. Terex’s domestic competitors have not suffered by importing their badged Japanese cranes ‘complete’—in fact they benefit in quality control (one source), testing efficiency and delivery flexibility, as the cranes can ship into ports convenient to the customer without having to be ‘finished’ at the US plant.

With the success of the IHI programme, the limited production of the old American designed machines was discontinued and other attempts to make use of the vastness of the Wilmington facility, including making towers and masts for Peiner tower cranes and acting as a receiving warehouse for imports of other European Terex products, ultimately weren’t viable. So 90 good jobs have been lost and with the market in the state it is, few crawler cranes are being imported anyway.

Terex is mindful of the need to continue to support the 700 or so IHI-Segment based Terex-American cranes working primarily in North America, as well as the many thousands of older American Crane and American Hoist cranes working worldwide.

In order to assure the availability of replacement boom and jib sections Terex has moved the necessary jibs and fixtures to its former CMI road machinery plant in Oklahoma City, Oklahoma. The company is planning to establish Terex-American boom and jib production at the plant there.

All other Terex-American parts support has been transferred to Terex's central parts operation located in Southaven, Mississippi while product and customer support is being relocated to a new facility in Wilmington.

But a local manufacturing presence remains important, and this was Terex’s only US crawler crane plant.

While it can be argued that customers are buying cranes made in China because of their lower prices, price-buyers rarely dominate the heavy capital goods market.

Just as Japan’s car, forklift and excavator makers learnt many years ago, the Chinese recognise the important influence of having local factories—as witnessed by the massive scale of their investments in manufacturing plants all around the world.

A hundred years of innovation
It is unfortunate that the market is in such a slump, for otherwise it should be a time for celebration of the crawler crane; it is exactly one hundred years since the first crane was mounted on crawler tracks. The innovator in 1911 was the Bucyrus Company of South Milwaukee, Wisconsin, and the first model was a Bucyrus gasoline-engine powered ‘Type 14’ dragline (usable with crane hook) sold to the Rio Grande Construction Company in Texas. The Type 14 had a standard 18.3m (60ft) lattice boom, a 4.27m (14ft) diameter swing ring and the crawler version weighed 47t (52USt).

Over these hundred years, while the product has evolved astonishingly, the genetic roots of the product are still clear to see. Along the way it has transitioned from steam and electric to gasoline and ultimately to diesel power: from a mix of timber beams and riveted fixed-length iron channel booms that offered just 20ft (6m) of reach to extendable lattice booms, robot-welded from ultra high-tensile fine-grain steel; from limited swing chain-pulled boom swing to full slew on hook rollers to smooth slew on fully-sealed lubricated swing bearings; from noisy clunky gears through power-assisted drum clutches to full hydraulic drive; and from 2t to 3,600t lifting capacity.

But the change in the ergonomics is even more dramatic. To operate an early crane or shovel you had to be a steam and mechanical engineer, with a body-builder’s physique. You needed to be willing to work a hard 12-hour day, year-round, through all kinds of weather, without cover or protection. And be prepared to help dig or pull it out when the ground gave way or it tipped over. No instruments. No manuals. No product support.

That the very first crawler crane/shovel was invented just seven years after the development of the first successful crawler tractor is quite significant. To take a revolving boom machine and apply it to an undercarriage that had simply functioned as a tractor took real insight and a recognition of the merits of the crawler: mobility over rugged or soft ground, low centre of gravity, a durable and low-cost structure, and a design that afforded a stable base from which to both lift and move materials.

That first fully functioning tractor had been designed, built and patented in 1904 by David Roberts, chief engineer of Richard Hornsby & Co, of Grantham in Lincolnshire, England. Ten years later the rights to the patent were purchased by Benjamin Holt (of Caterpillar fame); for although Holt had started testing a tractor with rear crawlers in late 1904, this was effectively a half-track relying on wheels at the front for steering. Hornsby would later merge with another excavator builder— Ruston, Proctor & Co. of nearby Lincoln— to form Ruston & Hornsby in 1918, who in 1930 merged with Bucyrus Co to form Ruston-Bucyrus Co.

By the 1920s a four-crawler mounting had been developed by Bucyrus for its Class 24 dragline. Manitowoc’s veteran crane designer John Lanning, or one of his colleagues, clearly have long memories, as the crowds at ConExpo 1999 witnessed when the 1,000USt four crawler base Model 21000 was unveiled.

By 1911 lattice booms were widely employed on fixed derricks, rail cranes, and tower cranes. Although the first (skid-mounted) dragline excavators built in the early 1900s used wooden poles or steel channel booms, with the need for greater reach and capacity came the use of long lattice booms. When Bucyrus entered the dragline business with the 1910 purchase of Heyworth-Newman, the first Bucyrus Type 24 dragline, introduced in 1911, had a 100ft (30.5m) lattice boom.

While draglines certainly aren’t ‘cranes’ they are about as close as it gets and can be employed as crane with the simple substitution of the dragline bucket by a hook.

To further reduce ground pressure on larger models Bucyrus doubled-up—employing eight crawlers, two per corner, on its Class 200 model introduced in 1927. Again Manitowoc has revived the concept, with the 2,300t (2535USt) 31000.

All of the early large crawler draglines and shovels swung through 360° on simple rings of very large diameter. In this field Bucyrus Company was a dominant force and its 115USt weight Type 24 used a ring of no less than 24ft (7.32m) diameter. This was decades before the development of enclosed ball or roller bearing slew rings.

Cranes like the Terex-Demag CC 8800-1 Twin show that the use of large diameter rings platform-mounted above the crawlers still has merit. But this concept had its first modern expression on Manitowoc’s 350USt (317t) capacity Model 7000, that offered a boom and jib combination of 122m +30.5m (400ft+100ft) free-on-tracks for offshore platform construction.

As early as 1911 Bucyrus was installing gasoline engines on its first draglines, and in 1914 P&H’s Model 210 crawler dragline offered gasoline engine power. In 1921 Bucyrus introduced the first use of a diesel engine on an excavator, and in 1932 Lorain offered the first (Caterpillar) diesel on its cranes.

Employing its experience building submarines for the US Navy during WWII, Manitowoc was the first company to use T-1 Steel (100,000psi) in its cranes. To handle the large hull sections, Manitowoc developed the first purpose-designed crawler lift crane, the 3900, originally rated t 65USt maximum capacity and introduced in 1941.

Although the use of welded fabrications on construction machinery was gradually developing during the first half of the twentieth century, it was 1945 when Thew Shovel Co. of Lorain, Ohio introduced the Lorain TL Series of small crawler and truck-mounted cranes and excavators that a completely welded superstructure fabrication was employed. Up until that time castings had been widely used, and continued to be popular for many years to come. Over 10,000 Lorain TLs were sold. The system of hook rollers connecting the rotating upper to the crawler (or truck) base preceded the development of the fully enclosed and internally lubricated swing (or slew) bearing, which initially used large ball bearings, and later roller bearings, to provide much smoother slewing of cranes and excavators.

The first ball bearing turntables were developed by Eisenwerk Rothe Erde GmbH in Dortmund, Germany in 1934 and in 1949 Rothe Erde introduced the double row ball bearing slew ring. In the interim, in 1946, John Lewis Grundon of Des Moines Dragline Service (later Little Giant Crane & Shovel, of Des Moines, Iowa) patented his design for a ball bearing slew ring. Despite this, in 1952 Thew Shovel Co., of Lorain Ohio was awarded a patent for its “shear ball” ball bearing slew ring. Starting in the 1950s, but gaining traction through the 1960s, the use of enclosed slew rings gradually replaced the older systems on cranes and excavators worldwide.

The ‘Skyhorse’ wheel-mounted counter-balancing counterweight was conceived of by Archer Brown and Jim Montgomery in late 1967, and patented in 1974, five years after the initial patent application was filed. They assigned it to their employer, American Hoist & Derrick Company. This proved a hugely-significant development, boosting mid-to-wide radius capacities by up to 600%. It remained an American Hoist exclusive, offered on its lines of crawler and truck cranes, until the patent expired and now such devices are widely offered on larger-sized crawler cranes.

Over the years, the issue of who built the world’s first fully hydraulic crawler crane has been the subject of various claims and counter-claims. Certainly Sennebogen (1969) and Hitachi (1971) have made this claim but neither holds the title. In fact it was Hy-Mac of the UK that in 1967 introduced the world’s first all-hydraulic crawler crane in the shape of the 35t capacity HM-1050. Although it took until the 1980s for the death knell to finally sound for mechanical crane drives, the development of hydraulic crawler cranes proved a leap forward that meant the development larger but lighter, quieter and more operator-friendly machines.

When Neil F Lampson of Kennewick, Washington State developed the Transi-Lift concept from its first beginnings in 1974 to the now established format with the auxiliary counterweight carried on a separate self-propelled crawler base, he moved the lifting capacity of crawler cranes into a whole new realm, with capacities now up to 3,000t and load moments in excess of 100,000tm. For some thirty years Lampson alone exploited this concept, until 2011 when both Zoomlion and Sany adopted this concept on their respectively 3,200t and 3,600t crawler cranes—soon to be joined with another Lampson-esque competitor in the shape of a 3,000t XCMG.

In 1976 Mannesmann-Demag introduced its freely-suspended auxiliary counterweight ‘Superlift’ device. Its first application was on the highly-successful 250t capacity Demag TC 1200 lattice truck crane, followed later that year on the new CC 1200 crawler. The device was patented in Germany and the UK but not in the US. This may have been as a result of existing art such as Manitowoc’s so-called “Liberace” crane built for DuPont in 1954 and employing a hanging rear counterweight. At first the device was only applied to increasing main boom capacities in the medium-to-wide radius range by as much as approximately 100%. Since then many manufacturers have employed this Superlift concept to such an extent that few crawler cranes of 500t or greater capacity are sold without this or a ‘Skyhorse’ type counterweight wagon.

The Ringer device was invented by Dan Beduhn in 1965 and tested in March 1967, using the Manitowoc 4000 crane, before being patented in 1969.

The device became a cornerstone of Manitowoc market dominance, and the patent was challenged by manufacturers including American Hoist and FMC Link-Belt, who successfully argued that the device should not be the exclusive domain of Manitowoc. In recent years ring-based cranes of extraordinary capacities have been developed, facilitating capacities of up to 200,000tm load moment.

Manitowoc's Model 31000 Manitowoc's Model 31000
Lampson Transi-Lift Lampson Transi-Lift
Terex's CC 8800 1 Twin Terex's CC 8800 1 Twin