Balling machines

PK tests with a thirty-two channel balls machine. J. Para-... 

Falling plunger and ball machines are generally not popular in Europe, but one design is specified in ASTM D2632. ASTM 1054 describes the Goodyear-Healey rebound tester. Figure 9.6 shows the principles of some of the tests. 

Phosphorus is present in zinc dialkyldithiophosphate and deactivate platinum catalysts in engine exhaust systems. Using zinc, antimony and oxothiomolybdate dialkyl-dithiocarbamate (MoDTC) complexes alone or in combination with other lubricating oil additives appears to solve this problem. Antimony complexes are used also as extreme pressure agents while molybdenum ones as friction modifier additives (Hill et al., 1994). Analyses of Zn(dtc)2 decomposition using the thermogravimetric method, flash vacuum pyrolysis, and four-ball machine... 

Nitrogen Four-ball machine 5.3kg thrust 700 540°C 30mins 220... 

Figure 13.4 Four-Ball Machine Load/Wear Scar Relationships for Oil with Molybdenum Disulphide or Zinc Dialkyidithiophosphate (Data from Ref,474)...

Four-Ball Machine later to study the interaction between molybdenum disulphide and several anti-wear and extreme-pressure additives and detergent/dispersant additives in a mineral oil. Unfortunately these results are difficult to compare directly with those of Thorp because he only reported wear scar diameters at two load levels. He found that at high load (lOOON) with 1 % of molybdenum disulphide, the combination with a ZDDP gave a wear scar diameter higher than either additive separately, and comparable to that of the base oil, and he described this as an antagonistic effect between the two additives. 

Figure 13.5 Four-Ball Machine Test Results for Base Oil Containing Molybdenum Disulphide and Zinc Di-lsopropyidithiophosphate (Ref.475)...

This remarkable ability to lubricate deformation of steel can be readily demonstrated in the laboratory with the two common test machines, the Shell Four-Ball Machine and the Falex Pin and V-Block Tester. As described previously in Chapter 5, lubricants with more than about 35% of molybdenum disulphide will result in extrusion of steel test pieces at temperatures little higher than room temperature. In both cases the surface area of the specimens is increased by about 200% at low power smoothly and without pick-up on the counterfaces. 

Pyrohydrolysis.—(a) Consistent analyses were, however, obtained by a modification of the pyrohydrolytic techniques described by Welsh and Parker and by Rushmere and Mason. The apparatus consisted of a silica tube, 40 x 2 cm., a 35/20 B.S. socket at one end, and a B.IO cone at the other to the last a Pyrex condenser was fitted. The steam-preheater and steam-trap, of J in. copper tubing, were linked to the 35/20 B.S. socket by means of a brass ball, machined to fit. The silica tube was heated in an electric furnace, and its temperature was measured with a thermometer. The steam was generated in a three-necked 1-1. flask provided with an air-inlet, an air-steam outlet, and a thermometer. 

When tested in the four-ball machine, solutions of sulfur in petroleum oils of moderate viscosity or in white oil raise the critical load for the onset of severe, destructive wear, which is designated as "antiseizure" action in the technological idiom of the four-ball test. Davey [54] found a significant increase in the critical initial seizure load from 834 N (85 kg) for a petroleum base oil to 1275 N (130 kg) for elemental sulfur dissolved in the oil. Sakurai and Sato [55] observed a 3.2-fold increase in the load-wear index (mean Hertz load) for a 0.5 weight-percent solution of elemental sulfur relative to that of the uncompounded white oil. The load-wear index is a specialized result of the four-ball test that can be taken as indicative of the average antiseizure behavior of the lubricant. Mould, Silver and Syrett [56] reported a load-wear index ratio of 3.08 for 0.48% sulfur in white oil relative to that of the solvent oil, and also an increase in the initial seizure load from 441 N to 637 N (45 kg to 65 kg) and in the 2.5-second seizure-delay load from 490 N to 833 N (50 kg to 90 kg). 

A direct comparison of the additive behavior of neutral phosphates and phosphites in the four-ball test under relatively mild conditions is reported in the work of Goldblatt and Appeldoorn [43]. The data shown in Table 11-15 are their findings for 3% of the additive dissolved in a heavy white oil and run in the four-ball machine for 15 minutes at 1200 rpm. In wet air all the phosphates show about the same wear im.provement under a 10 kg load over wear with the base oil in dry argon there is no significant improvement. Tributyl phosphite functions consistently poorer in the wear test than either triallyl or triphenyl phosphite, whose behavior is not significantly different from that of the corresponding phosphates. All the additives improve the performance of the... 

On the other hand, Fein s [49] extensive study of transition temperatures and scuffing in pure sliding with the four-ball machine showed the same type of response to the velocity/load ratio that he found with the two-disk machine [44]. The sliding speeds ranged from 0.0002 to 68.6 cm/s, the loads from 19.6 to 88.2 N (2-90 kg). Two kinds of steel specimen sets were used hardened AISI 52100, diamond pyramid hardness 740, and heat-treated AISI 4140, hardness 270. There were 13 different lubricants, with the properties shown in Table 15-7. At low rubbing speeds the interfacial flash temperatures were negligible and the bulk temperatures of the lubricant were taken to be the transition temperatures. At speeds above 0.359 cm/s a particularized form of the flash temperature equation was used to calculate the contribution from interfacial rubbing to be added to the bulk temperature to obtain the transition temperature. 

Another instructive investigation of the effect of temperature on chemically reactive additives is that of Sethuramiah, Okabe and Sakurai [55] with the four-ball machine to determine the welding load by the one-minute procedure at 1440 rpm (54 cm/s). Two types of frictional behavior were observed at the welding load, as diagrammed schematically in... 

The relation between structural types in silicones and wear or friction control has been studied from several points of view. Brown [16] prepared a series of methyl alkyl polysiloxanes whose properties are shown in Table 17-8. The results of their wear testing in the four-ball machine is seen in Fig. 17-5. The sharp drop in wear as the size of the... 

Seizure load is the highest value of the pressure at which the friction force moment exceeds 10 N m. In the four-ball machine used in the experiments, the loads range from zero to 7200 N. Several of the solutions tested reached the maximum load value without undergoing seizure. The 7200-N value is nearly two times higher than the seizure load for water (3700 N). The dependence of seizure load on concentration and type of compound is presented in fig. 17.12. 

There has been little systematic study of liquid lubricants for use below this temperature, lonsuprisingly in view of the limited number of potential applications. Ultra-low temperature operations such as those in space and liquid fuel handling have tended to employ conventional dry lubricants. Zaretsky et al (7) describe the testing Of oligomeric perfluoroethers in a rolling il-ball machine between -l8 l c and - 50 C. From the nature of the rubbed track, the authors inferred that the lubricants were providing EHD protection under these conditions. 

Structural information obtained by the survey should be used to ensure that the intended method of work retains the stability of the parts of the structure or building which have not yet been demolished. The aim should be to adopt methods which make it unnecessary for work to be done at height. If this cannot be achieved then systems which limit the danger of such exposure should be employed. The use of balling machines, heavy duty grabs or pusher arms may avoid the need to work at heights. If these methods are possible, the contractor must be satisfied that sufficient area is available for the safe use of the equipment, and that the equipment is adequate for the job. 

Piecemeal demolition is done by hand, using hand-held tools, sometimes as a preliminary to other methods. Considerations include provision of a safe place of work and safe access/egress, and debris disposal. It can be completed or begun by machines such as balling machines, impact hammers or hydraulic pusher arms. Considerations... 

Results for the four-ball machine fall into two categories, which correspond with the two principal modes of operation. 

IP Standards for Petroleum and Its Products, Part 1, Rolling Contact Fatigue Test for Fluids in a Modified Four-Ball Machine , Vol. 2, pp 300.1-300.11, Institute of Petroleum, London, John Wiley and Sons, 1986. 

Rolling Contact Fatigue Failure - Modified Four Ball Machine Method, Standard Methods for Analysis and Testing of Petroleum and Related Products, ( 992), Vol 2, pp. 300.1-300.7. 

The material selection process is kind of like playing a pin ball machine. You start flipping through the process, adding up the points, when all of a... 

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