THE STORY OF THE P&H MODEL 2800
By Richard “Chubby” Czubkowski
This 2800 Story is dedicated to all the original R&D Group, who through their skill, dedication and forward looking design innovations has made the “The P&H” # 1 in electric rope shovels.
To all the unmentioned people in this story, who worked on ELECTROTORQUE and CENTURION, this story is also about you and your dedication and hard work to make the P&H Mining Shovel the best in the world.
To Les Price, who was instrumental in the 50’s in pushing forward the control design of electric mining shovels. Les was the mentor to two novice electrical engineers who stated on the project in 1961.
To Jack Taylor who promoted the design concepts, constriction and selling the 2800.
To Henry Harnischfeger and the Mining Division of the Harnischfeger Corp., who promoted and funded the new big shovel.
To Richard Profio, who started in 1969, was quick to grasp the importance of the 2800 and used his experience and engineering skill to make the 2800 the premier mining shovel to the mining industry. The writer traveled with him to all parts of the world and leaned about mining, the business of mining and an appreciation of miners and what they wanted in a good shovel
To Tom Weber and his dedicated Engineers and designer who carried on the design of the 2800 with innovations. It saddens the writer that Tom never saw the 2800 MKII turn into the 2800XPC.
To Gerry Schmidt and his team of motor designers for the DC and AC shovels motors.
To all P&H Engineers who advance the digital control called Centurion and the advance diagnostic and remote monitoring systems to keep the 2800XPC #1 shovel in the world.
A special acknowledgment and dedication to my long friend and fellow engineer Frank Clewell. His knowledge as an electrical engineer and his practical knowledge of mechanical things was evident in the cabinet assembles he designed. Some of his cabinet designs are used today on the 2800XPC.
2019, marks the 50th anniversary of the P&H 2800 Electric Rope Shovel. The first of four 2800’s were built in Main Plant in West Milwaukee, WI, were erected and went to work at the Kaiser Resources Balmer mine, near Sparwood, British Columbia, Canada in 1969-1970
The 2800 was a radical departure from the electric excavator designs of the last three decades ago. For the first time, the mining world was introduced the biggest hard rock loading shovel , on one set of crawlers and a pioneer static convertor control of DC motors called P&H Electrotorque
The concept of a big loading shovel started in the early sixties by a small group of dedicated engineers and detailers. They were lead by Les Price, promoted by Jack Taylor and Henry Harnischfeger.
The roots of the 2800 go back 135 years. The writer tells the story about the Pawling & Harnischfeger Corporation; its beginnings and the origin of the phrase referring to Harnischfeger equipment as “The P&H”. Without this past history, the 2800 may not have come into realization
The writer tried to relate the story of the 2800, as he and others remembered it. Almost six decades have past and some of the original engineers and memories also have past.
Harnischfeger Corp. had gone though several major changes with new people and with the loss of past history. The 2800 and the history of a company, which goes back 135 years, should not be lost.
THE BIGGINING of P&H ---------------------------------
“THE P&H” ----
Industrial artisans Alonzo Pawling and Henry Harnischfeger started the manufacturing business that would evolve into P&H Mining Equipment in Milwaukee, Wisconsin USA.
Pawling was a castings pattern maker. Harnischfeger was a locksmith machinist with some engineering training. Both individuals served within the Whitehall Sewing Machine Company factory in Milwaukee. Pawling exited the firm to start a small gear machining and pattern making shop in 1883. Pawling persuaded Harnischfeger to join his firm as an equal partner. Their Pawling & Harnischfeger Machine and Pattern Shop officially began on December 1, 1884.
Pawling and Harnischfeger initially supplied industrial machinery components and assembly service support to large manufacturing operations in Milwaukee. Their customers included industrial knitting machine manufacturers, brick makers, grain drying equipment manufacturers and beer brewers.
In 1887 an overloaded overhead bridge-type crane collapsed within the foundry operations of a nearby heavy equipment manufacturer. Pawling and Harnischfeger rebuilt the crane with an improved and simplified design eliminating the rope and pulleys with a set of electric motors and transmissions. With their immediate success they moved into the overhead crane manufacturing and the service business.
A bank panic in 1893 caused demand for cranes to plummet however, prompting them to look for another product line that might help them reduce business risk amid economic downturns.
Their loyal customers referred Pawling & Harnischfeger as” P&H” and to this day loyal customers refer to their equipment as “The P&H”.
EARTH MOVING MACHINERY ERA BEGINS -------------------------
By the early 1900”s, they were experimenting with digging machines for construction and mining. In 1903 the manufacturing was moved to a 20 acre site in West Milwaukee Wisconsin. In years to come this was known as the” Main Plant” or “National Avenue”.
By 1920, their engineering and manufacturing operation introduced a rugged mechanical shovel named P&H Model 206. It was rated as a ½ cubic-yard and 500 pound pay load. By 1926, P&H digging machinery was effectively in distribution around the world.
Though the years P&H built mechanical earth moving machinery like giant Trenchers, Soil Stabilizers, Pushers(dozer) , Tampers, an experimental Self Loading Shovel and one of a kind machines lost in the archives.
From an “Autobiography of Henry Harnischfeger” December 1929 – Milwaukee, WI
Last paragraph ----------------
“As I write this sketch, in March, 1929, it is with a feeling of satisfaction that my many years of struggling and hard labor have been rewarded with a business and an organization that any man can well be proud of.”
Signed by: Henry Harnischfeger
ELECTRIC ROPE SHOVEL ERA -----------------------------
Ward Leonard Controls ----
Over the ensuing decades, P&H earth moving machines evolved into larger, more powerful and more productive prime movers of material. Bucyrus Erie and Marion Power Shovel produced bigger machines which were powered by steam.
In 1930, welding technology made it possible to the fabrication of lighter, stronger machinery versus traditional riveted-design machinery.
P&H not only was an early adapter to welded design, but the firm also designed and manufactured its own line of electric arc welding machinery and welding rod products.
Another technology advance applied to P&H digging machines during the 1930s was the Ward-Leonard DC electric motor drive system. P&H began designing and making their own electric motors and controls starting in 1893 when they acquired the limited assets of the Gibb Electric Company.
Bucyrus Erie and Marion Power Shovel had already started to produce electric rope shovel in the 5 CY range. P&H was well aware of this competition.
The following report may have been the basis for the beginning of the electric rope shovel business.
Excerpts from the engineering report;
PAWLING AND HARNISCHFEGER CO.
THE FIELD OF APPLICATION FOR WARD LEONARD ELECTRIC SHOVELS
“The discussion herein covers only a portion of the larger question of “Some of the Commercial and Engineering Factors Governing Successful Entry into the Ward Leonard Shovel Field which will be written up in sections as the demand for it rises. The question as to the field is the most important and is therefore discussed first. Wherever statements are based on anything other than definitely known facts these statements are so qualified. The sizes of excavators considered are the two, three, and four yard struck measure shovels and the corresponding draglines.”
H. S Jacobs, Electrical Engineer – October 19, 1931
The W-L System was typical of the time. A controlled rotating exciter (generator) was used to power the fields of the large DC generator delivering DC power to the DC motor to do work. P&H had acquired the Hansen welder design and modified it to be the exciter. Since the AC prime mover and the DC generators and motors were a product of P&H they all could be modified to give ideal characteristics to do work.
These electric shovels had a dipper capacity of 2.0 to 4 cubic yards. They were models 1200WL, 1225Wl. 1250WL, 1300WL and 1400WL. This was the origin of the traditional model designation; Dipper Capacity in CY x 1000.
In 1946 P&H experimented with an Eddy Current clutch for Hoisting power. Various forms of cooling the clutch were tried. P&H through experiment and engineering, adopted the air cooled Eddy Current clutch to power its hoisting motion. The Eddy Current clutch characteristics were ideal for hoisting the dipper though the bank material. The clutch maintained maximum torque up to full hoisting speeds. The rest of the motion controls were adaptations of the traditional Ward-Leonard system.
Since P&H was the manufacture of the motor and the control, P&H Engineers took advantage simplifying and optimizing the shovel performance and controls.
P&H SHOVEL CONTROLS ----------------------------------
IMPEDANCE CONTROL with MAGNETORQUE HOIST -----
The rotating exciter was eliminated. The operator signal, produce by a rotating induction master, was feed into a ‘large’ saturating reactor. Its output was rectified and the current feed to the generator’s fields. These were not closed loop controls but the differential fields of the generators controlled and limited the motion characteristics.
MAGNETORQUE clutch current was controlled directly from the induction master, through the rectifiers, directing the current to the fields of the outer member. Since all the current for the Magnatorque control as feed through the induction master, all P&H operators had very large bicep on their right arm.
ELECTRONIC TUBE CONTROL with MAGNETORQUE HOIST -----
In the 50’s, the THYRATRON TUBES were available for control rectifier service. They offered a simple device, no moving parts, to amplify an operator’s signal to control the fields of the generators. This system was short lived but they the basis of control for the new solid stated device call a SCR.
ELECTRONIC CONTROL with MAGNETORQUE HOIST -----
A new electronic device called a SCR, Silicon Controlled Rectifier (Thyristors), came on the market. Again P&H, through its own Engineering and innovation, used this device to control the operator’s signal to produce current for the generator fields. The 70 AMP SCR’S were controlled by a MAGNETIC FIRING ASSEMBY (MFA). Generator field current was provided by a single phase, center tapped full wave bridge.
The control system was a closed loop control with speed and current limits. The operator’s controllers were unique. A series of brushes ran on a special printed circuit board plated with Rhodium for long life. The resistors inserted tapered the output to match the proper feel of the shovel motion.
Due to the popularity and sales success of P&H shovels, P&H was considered by GE as one of the biggest users of the 70a., stud type SCRs. This was a simple but effective control which stayed virtually the same for the 2100 and smaller models to this day. This control was called ELECTRONIC CONTROL with MAGNETORQUE HOIST. The control was effective, simple with few parts, easy to work on and to correct problems.
EXPANSION AND MINING CHANGES--------------------------------
Harnischfeger hit its stride during the postwar industrial boom in 1957. Engineers, Systems and Production people were needed and hired. In 1959 Walter Harnischfeger became chairman of the company and his son, Henry, became president. During this period, industries were becoming more complex, and Henry Harnischfeger felt challenged to choose between being an average competitor in several tough fields or the leader in two or three. Between 1964 and 1968, Harnischfeger streamlined its operations.
The Construction and Mining Division and Electrical Division were formed. Mineral and metal prices for were coming down. These raw materials were getting harder to mine and their yield was also coming down. Mining had to be done on a large scale for more volume, at a cheaper cost with reduced labor. The existing shovel fleets were old. It seemed like the 15 CY machines and 85 ton to 100 ton truck fleets were inadequate to meet their objectives.
SHOVEL SURVEY ------------------------------
In the late 1950’s , a P&H survey brought to light that the shovel market wanted a new family of bigger shovel, to make them compatible with the bigger trucks being proposed.
The survey highlighted;
The time was right for a new shovel and for P&H to maintain its leadership role as a shovel supplier. The engineering departments were re-organized to focus on new product developments while maintaining strong production engineering departments.
The Product Development teams, in the early 1960’s, were housed in a remote office at 38th and Burnham St., known as PROGRESS HALL. Here the Shovel R&D as well as other products such as Hoists, Motors, Electrical Products and Construction Equipment was developed. It was a time for the new organization, new leaders and with new faces to get started with new product developments
Shovel R&D Group-------------------------------
The R&D Shovel group, mechanical and electrical was under Chief Engineer Les Price. The mechanical group consisted of experienced Engineers and Designers; Carl Schneider, Bill Zimmermann, Unban Gall, Henry Barron, Carl Schocka , Roy Clements, Jon Lenich, Harold White and Matt Teitze. Matt was an Electrical Engineers, who work on Magnatorque development, was assigned to design the big pieces of electrical gear which were required on the big new shovel and the ventilation of the machinery deck.
The electrical group consisted of two recent graduates, Frank Clewell and Richard Czubkowski, with limited experience in designing shovel controls. Under the guidance of Les Price, the new Engineers completed their engineering training programs. They would become familiar with shop practices like assembly and wiring of electrical panel, testing Magnatorque shovels, Motor manufacturing, lab work and field experience on a variety of P&H shovels.
Mechanical Tools and Design -------------------
The Mechanical Group consisted of experienced machine designers. Their tools were parallel rulers, drafting machines, pencils, velum, look up tables, notes from previous designs and side rules; No CAD, no PC’s, no 3D printers etc. Stresses, load moments and various mechanical calculations were done by hand with a slid rule and adding machine.
Layouts were done with pencil on Velum paper and the detailers had to draw the individual parts taken into account the fit and production practices. Some designers would use the point on a dart to accurately make the layout dimensions more accurate. The four function calculators were rare. Slide rules and pencil on paper were the tools of choice. Stress analysis by computer was in its infancy.
Many new and innovated ideas were discussed. New revolving frame, dual hoist motors, propel motor in the lower, skid steer mechanism with V brakes, 25 CY dipper, bigger crawler shoes, side frame and lower, ventilation and lubricating systems etc, etc
Electrical design ---------------
Since there were no articles or written papers applying static converters to shovel motions with DC motors, Frank Clewell researched technical papers applying converters to DC motors. Big converters had been applied to dc motors but these were rather steady powering loads. Many control rectifier configurations had been applied in the past using Thyratron or Ignitron tubes.
More modern large Thyristors had been applied to railroad DC motors. GE had books explaining how to configure convertor bridges and how to produce controlled DC.
With this expanse of background studied data, the converter bridge configuration and application to the motors was designed.
The P&H Electronic Control used the Magnetic Amplifier (MFA) for control. It was a simple method to control the 3 PH, 6 Thyristor bridge. Richard Czubkowski deigned a squire wave excited magnetic amplifier with control windings for bias, voltage and current feedback, stability and operator signal functions.
Meanwhile the motor engineering were designing a low speed, high torque DC motor for fast response, especially suited for the static convertors supplies and mining shovels. These were the F series of motors. To enhance the required transient commutation requirements, a laminated field ring structure was employed. This greatly enhanced the interpoles function, resulting in excellent transient commutation. The resulting design with large commentators and armatures, proved as asset to the new innovated shovel’s control design as well as the shovel’s performance. .
The new P&H DC motor was a radical departure from the standard type, spilt frame mill type motor, as normally used.
Motors were also designed by a slide rule, hand layouts and past experience.
DESIGN PARAMETERS OF THE “BIG SHOVEL” ESTABLISHED ---------
The goal of P&H R&D Engineering was to design a new bigger shovel which is to be; new, innovative, with new technology, and a giant leap forward in mining shovels.
Memories OF 1962 DISCUSSIONS ---------
The mechanical design was for an 18 – 25 CY dipper. To lessen the suspended load the dipper back was designed to act as the torsion box for the sticks.
Urethane bumpers were used in between the handle and dipper bottom to save weight
The crowd gearing is subject to destructive shock loading. A design was proposed to create a gear with a urethane segment, as a shock absorber, between the hub and outer gear ring.
This was abandon for a v-belt and sheaves, between the motor and crowd gear box.
The central oil lube system was to be heated by induction heating. This was abandoned and conventional thermostatically controlled insertion heaters were used.
Mechanically, there were many design and production problems that needed resolution before gears, shafts, heavy weldments, structures, castings, forgings etc., could be made. Many of these part and structures were new, big and heavier than seen before in production.
Since the application of static converters was new to mining shovels and new to P&H, a system was proposed for lab experimentation.
In 1963, with the new swing sized motor, flywheel, new MFA’s, new larger field and armature size thyristors, were set up in the mechanical-electrical lab in old BLD. 41. A flywheel was attached to the motor.
The objective was to simulate a swing drive. It was to be a torque drive, four quadrants with reversing fields for motor direction.
The transient protection, over current protection etc. had to be designed and built in the lab. The entire control system was a contained on a vertical plywood panel so that changes and failed parts could be easily replaced.
The lab experiment soon showed the MFA’s were too slow to respond to the needed firing angle of the bridge thyristors for good control current. An armature reactor was manufactured and connected to lessen the di/dt of armature current. A large air gap used to limit the residual flux in the core.
An experiment was tried, using powerful ceramic magnets, to negate the residual flux and increase inductance. This was futile a experiment because after a short time the magnets reversed there polarity and became useless.
The experimentation went on and a torque drive was functional, but not ready for a shovel. The MFA approach essentially did not work for the dynamic requirements of the shovel motions for the control of armature and field currents. It was a learning experience.
The control and motor setup was and eventually used to life test the crowd belts used on the first 2800’s and future machines.
Two related stories ----------------------------------------
The experimental converter system started early in 1962 in the mechanical/electrical lab in old Bld 41. It was Nov. 1963; we were ready, for the first time, to apply reduced voltage to the converter mock-up. Suddenly H.S. Jacobs, who was the father of the Magnatorque development, came out of his lab offices and announced President Kennedy, had been shot. He got the information through his broker and ahead of the information to the general public.
Story #2 --------------------------------
The setup and motor –flywheel was visible to people going through the lab.
Mr. Walter Harnischfeger was on his once a week visit to BLD. 41. He and H.S. Jacobs (Jake) were good friends. Mr. Harnischfeger nickname for Jake was “Bus Bar”. Both like to discuss politics and discuss money.
One day Mr. Harnischfeger stopped and approached us. He asked what we were doing. After a lengthy discussion he asked what the things were on the control setup board. We told him about, resisters, capacitors, diode, MFAs etc. He positioned his black hat, rolled the cigar in his mouth and said they look like the things that always burn out in my TV.
He admonished us to use good parts that would not burn out. The Chairman of the Board had spoken. We said ----- Thank you Mr. Harnischfeger. Fortunately he did not offer us one of his black hand rolled cigars.
( Also available in a downloadable PDF file. )