Welcome to vulcanhammer.info, the site about Vulcan Iron Works, which manufactured the durable air/steam line of pile driving equipment for more than a century. Many of its products are still in service today, providing reliable performance all over the world. There’s a lot here, use the search box below if you’re having trouble finding something. Also look at the end of an article, there are helpful links to more information with every post.
Here we link to the operations manual (or “Certificate” as the Russians referred to it.) We trust that you will find this informative as to the operation of this concrete pile cutter, which (to our knowledge) has not been duplicated elsewhere.
Yu. V. Dmitrevich, VNIIstroidormash L.V. Erofeev, Stroifundamentservice V.A. Nifontov, Stroifundamentservice D.C. Warrington, Vulcan Iron Works Inc.
This article was originally published in 1993 or 1994. The graphic above shows a 9 kJ unit mounted on an excavator.
Hydraulic demolition hammers mounted on hydraulically powered excavators are becoming increasingly widespread in world practice. They allow the excavators to be used for breaking rock and permafrost, break up large rocks, old foundations and reinforced concrete structures, and other jobs.
Outline of the Machine
Hydraulic demolition hammers are often equipped with hydraulic accumulators in the pressure line and sometimes in the drain line as well (as is the case with the Raymond hydraulic pile driving hammers) to achieve higher efficiency and to smooth pulses of fluid pressure in the hydraulics. Compressed nitrogen is mostly use as the elastic element in these accumulators.
The proposed hydraulic hammers differ from similar machines of leading companies outside of Russia such as Krupp of Germany, Montaber of France, and NTK in Japan. The main difference is in the accumulators the Russian machines have no compressed nitrogen accumulators, but are equipped with hydraulic accumulators having a so-called “liquid spring,” which is a closed volume of hydraulic oil compressed under pressure four or five times the pressure in the hydraulic system. Possible leaks from the inside of the hydraulic spring are compensated automatically when the hammer is switched off. Such a hydraulic accumulator does not need any adjustments and control during operation and its parts can serve as long as the hammer itself.
The main reason this design was chosen relates to the conditions in Russia itself. The temperature gets very cold, down to -60° C under these conditions the rubber in the bladder type gas accumulators will become embrittled in the temperatures common in many parts of Russia. Once this has happened, the bladders will burst and the machine will have to be completely disassembled and the bladder replaced. This operation is tedious enough on a normal construction site it is a greater problem when the job is somewhere above the Arctic Circle in Siberia.
Another specific feature of these hydraulic hammers is that their rams are not integral with the piston but are connected with the latter through a special elastic hinge. All the hydraulics of the hammer are centralized into a separate unit comprising the working cylinder, distribution valve and hydraulic accumulator. The ram can be of any size as required. The weight of the ram is selected so as to provide the impact energy at an impact velocity of no more than 6 m/sec. The weight of the ram is generally double that the the impact tool with other machines, it can be only half. This provides a high impact efficiency and increases the efficiency of the hydraulic hammer as a whole.
The power output of an impact hammer is the product of the impact energy of the hammer and the number of blows per minute. Thus, for the same power output an impact hammer can have either a high number of blows per minute and a low rated striking energy or a low number of blows per minute and a high impact energy. The advantage of the latter condition, however, is that the higher impact energy can be decisive in producing the high impact force levels necessary to demolish the work at hand. This is why these units have demonstrated outputs two or three times as high as those produce by Kone (Finland,), Krupp (Germany,) and have also outperformed those from Ingersoll-Rand.
The efficiency of these hammers is further promoted in breaking permafrost and rocks by the streamlined shape of the tool itself, which permits the operator to sink the whole hammer into the medium to a greater depth than just the length of the impact tool, i.e. a deeper layer than can be broken at one pass. Thus, there is no need to make the tool very long and the hammer can be operated as a lever, tearing large pieces away from the permafrost or rock. Other companies prohibit such handling of their demolition hammers. The strength of the tool and of the hammer body permit such operation in the case of the Russian machines.
Table 1 shows the standard sizes of the hydraulic demolition hammers based on these principles.
Table 1 Specifications for Hydraulic Demolition Hammers
Impact Energy, kJ
Blows per Minute
Hammer Weight, kg.
Ram Weight, kg.
Weight of Impact Tool, kg
Insertion Diameter for Impact Tool, mm
Hydraulic Oil Consumption, l/min
Working Pressure, MPa
Connecting Hose Size, mm
Weight of base excavator, metric tons
Maximum depth of loosening of permafrost or rock per pass, mm
The Size I has been produced in Belarus since 1982 and the Size IV in Russia since 1978. Sizes II and III have been tested as prototypes and are proving to be the most popular sizes. The design of the hammer is patented in Germany, Hungary and Finland.
Hydraulic hammers of Sizes IV and V may be used for driving small piles after some modification.
Description of Design
The hydraulic demolition hammer is mounted onto excavators as an interchangeable tool by means of an intermediate bracket which is secured both to the excavator and to the hydraulic hammer
Figure 1 shows the main parts which constitute the structure of the demolition hammer. The working cylinder (Figure 2) is essentially a body having a heat treated steel sleeve inserted therein, the latter accommodating a piston moving therein. The body of the work cylinder accommodates a check valve and a hydraulic accumulator comprising a piston with a head and rod, a bushing and a fluid spring enclosed in the cavities bored into the body and communicated with each other and with the rod end of the accumulator by means of ports.
Figure 2 Working Cylinder 1) Casing 2) Sleeve 3) Accumulator Bushing 4) Accumulator Rod 5) Piston 6) Check Valve 7) Lid 8) Check Valve 9) Piston Rod
As shown in Figure 3, a plug is provided to let air out from the cavity of the fluid spring when the latter is being filled with the working fluid.
The rod of the hydraulic accumulator is spring loaded. The head end of the accumulator is communicated with the fluid spring through a check valve intended to compensate for leaks from the cavities of the fluid spring when the hydraulic hammer is switched one and off. The work cylinder is closed from the top with a lid.
The impact portion of the hydraulic hammer is suspended from the rod of a piston by means of rubber shock absorbers. These decrease the dynamic loads acting on the rod. The impact portion moves in the guide pipe. Ports are provided in the upper and lower portions of the guide pipe and these intercommunicated by air ducts. With the impact portion moving, air flows freely from one cavity into the other one through the air ducts.
The impact portion delivers by its lower end blows upon the tool, which can move freely downwards for 60 mm along the guide of the axle box mounted on the guide pipe.
Principle of Operation
Looking at Figure 4, the ram, rod and piston are in their initial position, which is resting on the impact tool. The control valve occupies the upper position under the action of a spring mounted under its lower end position. This communicates the rod end of the work cylinder with the pressure line. It also communicates the head end with the drain line of the hydraulic system, the piston of the hydraulic accumulator occupying the upper position.
Figure 4 Operating Principle of Hydraulic Hammer — Beginning of Cycle, Ram in Bottom Position 1) Impact Tool 2) Body 3) Ram 4) Rod 5) Rod End Cavity 6) Piston 7) Check Valve 8) Drain Port 9) Head End Cavity 10) Duct 11) Control Valve 12) Accumulator Piston 13) Drain Line 14) Pump 15) Fluid Spring Cavity 17) Spring
Figure 5 Operating Principle of Hydraulic Hammer — End of Upward Acceleration 1) Impact Tool 2) Body 3) Ram 4) Rod 5) Rod End Cavity 6) Piston 7) Check Valve 8) Drain Port 9) Head End Cavity 10) Duct 11) Control Valve 12) Accumulator Piston 13) Drain Line 14) Pump 15) Fluid Spring Cavity 17) Spring
After the pump is started, the working fluid gets through the valve into the rod end of the working cylinder and the space above the piston of the hydraulic accumulator. As a result of this the impact portion starts accelerating upwards. This forces the fluid from the head end of the working cylinder through the port along the drain line into the tank, whereas the piston of the hydraulic accumulator moves downwards.
Moving on to Figure 5, at the end of the upward acceleration, the piston passes the drain port, as a result of which pressure in the head end of the working cylinder, the duct and above the upper end of the valve rises. Since the area of the upper end of the valve is greater than that of the lower one, the valve moves into the lower position, thereby communicating the head end with the pressure line and the rod end with the drain line.
This is followed by the phase of slowing the ram to a stop in the upstroke, whereby the piston forces the fluid from the head end into the hydraulic accumulator.
After the ram has stopped at the top of the stroke, it starts accelerating downward under both the force of gravity and the fluid pressure on the head end of the piston. After the impact portion has acquired a speed where it outruns the hydraulic pump, the hydraulic accumulator starts to discharge, and its piston moves upwards. At the end of the downward stroke the ram strikes the impact tool, which moves relative to the body of the hammer so the tool can penetrate the soil. Before the blow is delivered, the upper edge of the piston lowers below the check valve, whereby the head end is communicated with the drain line. As a result of this, the pressure in the head end and above the upper edge of the control valve drops down to a value at which point the spring mounted under the control valve can move the control valve upwards.
After this, the cycle can be repeated. Figure 6 shows the hydraulic schematic for the system.
The fluid spring is used in the structure of the accumulator. In this spring the pressure exceeds that in the hydraulic system by as many times as the area of the piston exceeds the area of the rod entering the cavity of the fluid spring.
Possible leaks from the cavity are compensated by the hydraulic system after the pump through the check valve, with the piston being displaced by the spring mounted thereunder.
The hydraulic hammer cannot be started unless it is applied against the work. Without the work being applied against the impact tool, the block head occupies the lowest position and the upper surface of the piston is lowered below the ports through which the fluid gets into the rod end. An attempt to start up the hammer without the hammer applied against the work results in the fluid passing freely over into the tank, and the hammer does not operate.
The hydraulic demolition hammer with fluid accumulator has proven itself both in theory and in practice. It has as rugged and simple design and is capable of performing many kinds of work. It overcomes many of the difficulties of other designs without unacceptable compromises in performance.
Intellectual-property protection, however, is deeply problematic. Previous agreements reached under US president Barack Obama’s administration could be reconstituted. But the jurisdictional enforcement of breaches is still hopeless.
One possible mechanism is to subject relevant contracts between Chinese and foreign firms to international commercial arbitration bodies in Singapore or Switzerland, designed to deal specifically with the enforcement of IP protection.
In both contracts Vulcan signed with the Chinese for the sale of the 560 hammers and boiler (1981 and 1983,) our agent Amtech wisely included the following provision:
18. SPECIAL PROVISIONS: Arbitration in Sweden or Canada
One thing that has always struck this observer as unwise is the typical American attitude that everything should be everywhere just like it is in the US. Old exporters (and Vulcan certainly had a good track record in that regard) knew better, but our voices have been ignored, especially in the years of US unilateralism following the end of the Cold War. The rise of China, whose view of life is very different from ours, should occasion the revival of a more “multilateral” approach, but such an approach will require a different style of mind than has been exhibited up until now.
On this site I have posted several articles on Soviet (and after that Russian) pile driving equipment, such as diesel hammers, concrete pile cutters, and vibratory and impact-vibration hammers. These are very specialised topics, even by construction industry standards; here I want to present some photos of more general interest to you heavy equipment fans. The Soviet Union was known for its commitment to heavy manufacturing and construction equipment like this is certainly a big part of that.
NPO VNIIstroidormash is the Soviet name for the Moscow-based institute which designed and tested the equipment shown below. The name means the All-Union Scientific Research Institute of Construction and Road-Building Machinery. It was put together in 1975, and survived past the end of the Soviet Union in 1991 as a share society, i.e., a privatised corporation. In addition to the pile driving equipment which got me involved with the organisation, it designed many other types of equipment, and the best way to show this follows, from their catalogue produced around 1986.
Vulcan first connected with the Institute in 1988, and our contacts continued for the next six years. Sometimes things got strange but we discovered an organisation that put out some very good designs for construction equipment. Unfortunately the Soviet manufacturing organisation was not up to proper quality control, especially in the civilian sector, and that weakness was one of those which ultimately brought the Soviet Union down.
In early 1994 I went to Russia for the purpose of visiting a factory in Bryansk, which is located at the meeting point of Russia, Belarus and Ukraine. This was not a factory producing high tech military hardware, but something more prosaic but important for our modern world: diesel pile driving equipment, used in the construction of roads, bridges and buildings.
Below: a YouTube video of the inside of this plant.
These were the days when the Russian Mafia reigned supreme, so we had to be careful. The plan was for me and my representative to cross Moscow via car and metro to the Moscow Kievskaya train station, board for a six hour “overnight” train trip to Bryansk, spend the day there, and return as we came to Moscow. Except for our plans for avoiding the criminal element, this wasn’t a very difficult trip.
So we made our preparations. No US cash, no credit cards. I even switched my wedding band to my right hand. We were planning on travelling light, but we had to have some spending money. So, as we prepare to leave, my representative whips out a wad of Russian cash and asks me, “Half a million roubles. Is it enough?”
I was boggled by the question. Not even family trips with my mother to the Ritz-Carlton cost half a million. But here the currency had collapsed with communism; the exchange rate was about 1300 roubles to the US dollar. So we were only talking about US$385, which was a reasonable sum considering that much of our travel (especially by train) was subsidised by the government.
Some of you reading this live in a place where the currency is parcelled out with many zeroes. But it’s interesting to note that, to my knowledge, no currency started out that way. If we look at major currencies today, we see that all of them are either “substantial” in their value (dollar, euro, pound) or were at one time (yen, and of course the rouble itself.) But there is a greater lesson here.
If Islamicism has done one thing, it has put monotheism on the front page of the news, whether the secularists like it or not. (And they usually don’t.) This is something, of course, that Islam has in common with Christianity and Judaism. But there are still many who believe that there are many gods. The most important representative of this is Hinduism, where literally millions of gods are resident and require worship of some kind. Mormonism for its part is more worried about its adherents becoming gods rather than worshiping a polytheistic system of same.
Then, of course, we have secular systems of “gods” which do not have spiritual divinity but have divine importance to their adherents. We think of people who are focused on their houses, their motor vehicles, their jobs, etc. These are pursuits that can pull you in many directions, to say nothing of run your finances down.
The central problem with any system of belief that affirms the existence of more than one God is this: the more “gods” there are, the less meaningful the whole idea of deity becomes. Like the roubles we took to Bryansk, there may be many of them, but they’re not worth very much. Both Russian roubles and Mormon gods are the product of the same process: too many of each were “created” for the intended purpose. Religions such as New Age and Mormonism attempt to exalt humanity by debasing divinity, but they end up debasing both. As with currencies, we are better off with one God who is worth it all than many which are, individually and frequently as a group, worth very little. The promise of divinity doesn’t look all that good when seen in this light; it is a mirage that vanishes as we approach it.
Hear, O Israel: The LORD our God, the LORD is one. Love the LORD your God with all your heart and with all your soul and with all your strength. These commandments that I give you today are to be upon your hearts. Impress them on your children. Talk about them when you sit at home and when you walk along the road, when you lie down and when you get up. Tie them as symbols on your hands and bind them on your foreheads. Write them on the door frames of your houses and on your gates. (Deut 6:4-9 from New International Version)
Socialist states love to trumpet their own successes, real or just propaganda. The collapse of the rouble left just about everyone in the Russian Federation with more than a million roubles (about US$770 in early 1994) of net worth. So I declared to my representative, “Seventy years of socialism, and everyone’s a millionaire!”
His response: “It was their greatest achievement!”
We did finally meet with the offshore oil people. It was strange too; when the babushka receptionist asked where we were from and we told them we were from the U.S., she jolted upward in her seat and exclaimed, “Oh, my God!” (this in an atheist state!)
Finally we had our closing meeting with our Soviet counterparts. This was during the age of perestroika, which simply means restructuring. This ministry was doing its own shuffle, so the chief negotiator unfurled the new organisation chart for the ministry. He spent a great deal of time going through everyone’s new title and position. Our agent got impatient with this presentation, so he thrust his finger at the centre of the chart and demanded, “Who’s this idiot?”
“That’s me!” the answer came back.
It doesn’t take being in a socialist organisation to make us feel that we’re “lost in the shuffle,” just another cog in the machine or just another “idiot” working in an structure that neither knows or cares whether we stay or leave. We get to the point where we look at ourselves and life in general in this way.
But that wasn’t God’s plan for us. We have a God who loves and cares for us, who created us and had a purpose for us from the beginning (“negative infinity,” as we say here.) Just because others who have their own purposes–if they have any clear objective at all–try to define us as part of their machine doesn’t mean that the God of the universe agrees with their assessment. He does not and neither should we. If we make him first in our lives, we will find his purpose for us and then we will never again be “this idiot.”
One of the most complicated transactions I have ever been involved in during my years at Vulcan was the purchase of the patent rights for a Russian concrete pile cutter (shown at left.) The patent had around a dozen inventors and two research institutes, spread out from Moscow to Vladivostok. The sheer logistics of getting everyone to agree to this, to say nothing of the financial considerations, made it a daunting task.
After six years of work on it we had actually made quite a lot of progress, but the Deputy Director General of the main research institute was trying to hold out for more money. Since the market for these things is pretty limited, we had to be careful.
At this point the Russian government sponsored a Russian technology exposition in Washington, DC, and the institute was one of the exhibitors. They sent their Director General; we thought it would be a good time to make some progress without the expense of another trip to Russia. So I went to Washington, was met by my translator, and we set out to have a meeting with the Director General.
On the way we stopped by the hotel room which the institute’s people were using as a headquarters. It was a mess; clothing and trash were piled everywhere, vodka bottles being the most prominent. Evidently these people were having quite a time during their trip to America.
We got to the exhibit hall and managed to pull the Director General aside for a meeting on the patent. In preparation for this meeting, I had prepared a “protocol” (we usually call it a “letter of intent” in the U.S.) which outlined what was for us an initial negotiating position. So I presented this and asked the Director General what he was prepared to sign to conclude this agreement.
At that, my translator looked me straight in the eye and said, “He is prepared to sign anything.” Needless to say, I wasn’t prepared for this; I was used to a lot more “horse trading” in negotiations, particularly with people outside the U.S. But sure enough, he was; he signed the protocol. Back in Moscow, his deputy was enraged at this, but there was nothing he could do; the negotiations were completed and we obtained the patent assignment.
We live in an age where people are said to be deceived by all kinds of “isms”: moral relativism, secular humanism, post-modernism, and the like. But having been in the real world for too long, I like to look at things a little differently. The problem with people today is that, after years of excessively rapid upward social mobility, blistering technological change, and relentless manipulation by those who own and operate the society, they are, like our Director General, prepared to sign anything, to go along with anything so long as their lives go on as they have, no matter what the long term cost is to themselves.
“For a time will come when people will not tolerate sound teaching. They will follow their own wishes, and, in their itching for novelty, procure themselves a crowd of teachers. They will turn a deaf ear to the Truth, and give their attention to legends instead.” (2 Tim 4:3-4) This is where we’re at, with the disintegrating families, eroding human rights, and the growing consumer debt which is turning a society of owners into a society of renters, at the whim of those who control the financial destiny of the nation. Christianity, which takes a definite stand on many issues, is looked on with hostility as a menace to the stability of this house of cards, proclaiming as it does an ultimate authority beyond the state.
But there’s always a payoff of some kind in the end. Our Russian inventors and institutes were paid off in U.S. dollars, a valuable commodity in Russia in those days. Those who sign with the rulers of this world have another payoff altogether: “The wages of Sin are Death, but the gift of God is Immortal Life, through union with Christ Jesus, our Lord.” (Romans 6:23) It’s your choice. Are you prepared to sign anything?
In 1988, during Vulcan’s first trip to the then Soviet Union, my brother Pem and I were given the chance to visit the Monastery of Trinity-St. Sergius, which was the administrative centre of the Russian Orthodox Church. This is located in the town of Sergeiev Posad, which was called Zagorsk during Soviet times. The trip was arranged by our Russian business hosts (V/O Machinoexport) and our Russian agent at the time, A.A. Titov. The article below was written 20:15:01 4/20/1988 (the day of the visit) with a few corrections in the text and updates at the end.
Christianity was first introduced to Russia from Byzantium (Greek Orthodox) between 860 and 867. At this time Kiev — south of the Chernobyl site — was the capital of Russia. In 957 the regent Olga was baptised in Constantinople; her grandson Vladimir made Christianity the state religion in 988. This is being celebrated this year as the 1000th anniversary of the “Baptism of Russia” and extensive celebrations are being made plans for as a result.
The Russian Orthodox Church is an Orthodox Church, and until 1448 was subordinate to the Greek Orthodox Church in Constantinople. At this time, as the Byzantine Empire was coming to an end with its conquest by the Ottoman Turks, the Russian church took the step of electing its own leader; in 1589 this leader, now residing in Moscow, took the title of Patriarch, making him in theory the equal of the Patriarch in Constantinople and also of the Pope in Rome.
In 1721 the Russian Tsar Peter the Great abolished the Patriarchate and replaced same with the Holy Synod to run the Orthodox Church. This was a council, with its head — a lay official — appointed by the Tsar. This effectively made the Orthodox Church a department of the government, a position it found itself in until the Tsar was overthrown in 1917.
With that overthrow the Church re-established the Patriarchate, but now the greater threat came of course from the Communists, who, following Marx, believe that religion of all kinds is the “opiate of the people” to dull their revolutionary drive, and which will wither away under the advance of “scientific” socialism such as their claims to be. The church’s property was nationalized and many of its clergy was jailed and killed, and parts of the church made themselves into a pro-Soviet type of church, a process that has been repeated with the Catholic Church in Nicaragua. Matters became especially desperate under Stalin, who attempted to destroy all opposition through liquidation in his purges in the 1930’s.
Matters were at their nadir when the Second World War broke out, and when the Germans invaded the Soviet Union the demoralization of the nation was so complete that Hitler nearly succeeded in conquering the country. In its desperation Stalin’s war effort turned to the Orthodox Church and other Christian groups to help with the war effort, to revitalize the people for the war effort. This they did, and in return the Soviet government has granted the Orthodox Church and some other Christian groups limited freedom of existence and activity. The Orthodox Church today runs a precarious balance today; on the one hand it attempts to carry on its liturgical and spiritual activities to nurture the flock in the Orthodox faith, on the other it must to secure its existence meet Soviet regulation and to assist the Soviet government in various activities, such as the promotion of the peace movement in the West, which is a major project of the Soviet regime today.
Outline of the Trip
Arrived about 1130 with Pem, Alex Titov, and Alexander Tikhanov and assistant Natasha from V/O Machinoexport. Were greeted at Monastery office.
We were first given tour by Father Alexander of several of the churches in the compound. Zagorsk is the administrative centre of the Russian Orthodox Church, founded by St. Sergius in 1337. The Orthodox complex is within the town itself, being a walled fortress, a format dictated by military considerations in past times, similar in concept to missions in our own Southwest such as the Alamo. The last time it was used for military purposes was against a siege by the Poles in the 15th century. These churches, such as the Trinity Cathedral (which contains St. Sergius’ relics), the Dormition Cathedral, the Church of the Holy Spirit, were very impressive. When not in liturgical use, these churches are the site for all kinds of devotions, such as prayers, adorations, and Bible reading, and, in the case of Trinity Cathedral, singing which has an ethereal quality beyond words to describe. Then we returned to office where we signed the guest register, and I wrote congratulations to them for the 1000th anniversary of what they call the “Baptism of Russia”.
After this, we were given tour of the seminary museum by a seminarian. This contains historical articles of the Orthodox church of all kinds and a special section on the life and work of the Patriarch Alexis, who helped bring the Orthodox Church back to life after its near extinction by Stalin. There was a scale model of a large cathedral in Moscow built to commemorate the victory over Napoleon in 1812. Titov asked what happened to it and the seminarian replied “What happened to thousands of other churches in Russia? There is a swimming pool where that one was.”
We then went to the seminary office, where we were greeted warmly by Father Vladamir Kucherjavy, Assistant Rector of the seminary, who then fed us snack. He gave us description of the work of the seminary, and in the process told that full course in seminary was a four year course followed by two year course, similar to our own BA/MA system; however, some went directly to the field after the first four years. This reminded me of our church’s internship program, so I asked Father Kucherjavy if the two were alike. He said yes, and then asked what church I belonged to. I told him that I belonged to the Church of God, that it was started in 1886, that it was the oldest Pentecostal church in North America, but that Russian Orthodox people had had the Pentecostal experience earlier. His first question was whether we were a member of the National Council of Churches or not, and I replied that we were not. I then explained that I knew about the Orthodox people because the founder of the FGBMFI, Demos Shakarian, an Armenian, had had grandparents and parents brought to it by these believers coming to Turkey from Russia. He then reminded us that this year was the 1000th anniversary; I replied that I was appreciative of this event. He said that they were more than that; they were working hard to make the actual celebration a reality this summer, including having to rebuild the seminary’s church after a disastrous fire two years ago. Having seen the restoration, I said that I was impressed with the speed of the work. He said, in effect, that I didn’t know the half of it! He went on to describe his travels in the U.S., which he makes mostly for Soviet sponsored peace groups. We then finished our session and he wished us good bye. I told him that I would tell those officials and such in our church of my visit, as I live in the denominational headquarters city and attend church with these people.
Note: the “large cathedral” was of course the Cathedral of Christ the Saviour, dynamited in 1931 under Stalin. It was in fact rebuilt during the 1990’s, which I discuss in my Easter piece Rising From the Pool. I did present this account to Church of God officials; the church eventually established a legal presence in Russia which it has to the present day.
Calculations of Main Details (Strength
Strength calculations assume that the inertial forces during impact are 150 times those of the weight.
We checked the rotor shaft strength in the optimal mode, i.e., when the impacting force direction formed a 90° angle with the direction of the blow. To simplify calculations consider that the forces act at one point. In the vertical place the shaft is loaded with impact inertia forces from the shaft weight and parts which are located on it.
where Q1 = inertial force from eccentric weight(s) and part of the shaft ahead of the eccentric.
Q2 = inertial force from the part of the shaft under the bearing.
Q3 = inertial force from the rotor weight and the middle part of the shaft.
A diagram of the shaft assembly is shown below.
A diagram of the beam forces in the vertical plane is shown below.
A diagram of the beam forces in the horizontal plane is shown below.
The forces which act on the shaft in the horizontal plane arise from the vibrating forces of the eccentrics.
The reactions in the vertical plane are
The reactions in the horizontal plane are
The bending moment in the vertical plane in section A-A is
In section C-C it is
In section B-B it is
The bending moment in the horizontal plane in Sections A-A and C-C is
and for Section B-B
The sum of bending moments in Section A-A is
In Section B-B they are
and in Section C-C they are
The bending tension is calculated in the same way at all points.
For Section A-A
For Section B-B,
and Section C-C,
The tension in this section will be much less because the calculations do not take into account the force from the rotor shaft. Calculation of the shaft deflection will be done in Part C.
The calculations consider that the shaft is of uniform diameter, equal to 62 mm. In the vertical plane the deflection is equal to
= axial inertial moment of cross-section of the shaft
E = spring modulus of shaft material = 2,000,000 kg/cm²
The deflection in the horizontal plane is equal to
The total deflection from horizontal and vertical moments is
In reality deflections will be smaller because we did not take into account the rotor forces.
Determination of Tensions in Vibrator Casing
The casing is subjected to loading tensions when the vibrator impacts on the pile cap. As the ram is located in the centre of the casing the critical sections are two perpendicular sections which are located at the planes of symmetry of the vibrator.
Let us determine the moment of resistance of the section which is shown in the drawing of bending tensions in this section, shown below.
This section is weakened by a hole for the ram but this weakness is compensated for by the local boss. So we do not take into account the hole and its boss.
The moment of inertia for the section relative to axis X-X is determined as
where = sum of inertial moments of the separate elements.
= sum of multiplication of squared distances from the mass centre of element ot the axis X-X by the area of the element.
The moment of resistance for this section is
The distance between the axes of the electric motors is mm. So the bending moment is equal to
The bending tension is equal to
Let us determine the bending tensions in the section perpendicular to the axis of the rotors. The section is shown in the drawing below.
To simplify the calculations consider the section of the casing is symmetrical and consists of two circles and two rectangles.
The inertial moment is equal to
The moment of resistance equals to
Let us now determine the bending moment considering that the load from the weight along the axis parallel to the rotor axis is distributed uniformly.
The bending tension is equal to
Spring Deflection Calculation
The maximum force for which spring deflection is required is P = 1000 kgf. The number of spring N = 2. The maximum deformation of the springs is f = 200 mm. The load for each spring is
As the springs are operating in relatively easy (not hard) conditions we can consider the permissible tension equal to 5500 kgf/cm². So the permissible tension per 1 kgf of load is equal to
The necessary spring stiffness is equal to
So we choose the spring with the following specifications:
Hardness of One (1) Turn
Number of Working Turns
Npad = 14.5
Total Number of Turns
N = 21.5
Tension per 1 kgf of Load
A = 11.18
Hardness of the whole spring
So the spring we have chosen meets all of the requirements.
Determination of the Geometrical Configuration of the Eccentrics
Consider that the balanced part of the eccentrics (I and II; see diagram below) cancel each other.
So the coordinate of the center of mass of the rest of the eccentric (in the shape of a sector of a circle) is determined by the equation
The weight of the unbalanced part of the eccentric for a 1 cm thickness is equal to 1.7 kg. The eccentric moment of this eccentric is
The dynamic force of the eccentric is
The angular speed is rad/sec. The necessary eccentric moment of the eccentric is
The necessary total thickness of the eccentrics is
As during the determination of the eccentric moment it was increased a little, consider the thickness of the eccentrics equal to 80 mm.
This configuration of the eccentrics which we have come up with gives us an increase of its weight in comparison with the weight which is necessary to provide the required eccentric moment. So decreasing the moment of the rotary parts makes it easy to operate the motors.
Sizing the Bearings
The rotor shafts are mounted to spherical, double-row roller bearings No 3614 which have a coefficient of workability C = 330,000. The rotor weight Gb = 25 kgf. The eccentric weight is Gg = 28 kgf.
For the calculation of dynamic loads consider that the accelerations during impact are equal to 150 times the free weight.
As the shaft is symmetrical, each bearing is subjected to half the dynamic load
The shaft rotates at n = 950 RPM. Consider a factor of safety Kd = 1.5 and a dynamic load coefficient Kk = 1. The durability of the bearing “h” is determined as