COST 532 WG2 Transmission systems meeting report

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COST 532WG2 Transmission systems - meeting
report

• Co-ordinator Joe Viintin, Marian Szcerek
• Norway Tromso, May 2004

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1 PROJECT STATUS Working Group Meeting was in
Brussels on 21 February 2004. The first
presentation introduced the aims and challenges
of the Transmission Systems. Working Group while
the project managers has presented the results of
8 started and planned projects. Currently there
are 11 running projects in WG2. Table 1 shows
the status and classification of the running
projects.
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2 PROGRESS ON DISSEMINATION AND EXPLORATION OF
RESULTS (TS)   I have received 9 project status
forms from project managers up to 25. May 2004.
The progress of the one-year running projects is
quite high which is indicated in the Table 2.
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3.   FRAMEWORK RESEARCH PROGRAM OF WG2-
TRANSMISSION SYSTEM   1. Power
Transmissions New Challenges                    
     

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• THE FUTURE TRENDS AUTOMATIC TRANSMISSIONS
• 2.1 Automatic Speed Change Transmission System
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• 2.2 Continuously (Belt or Chain) Variable
  Transmission System b-CVT
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3. NEW DEMANDS FOR LUBRICANT PROPERTIES  
3.1 Automatic Trasmission Fluids
(ATF)                                            
               
 
Aims of the ATF-s
        Power transmission         Working as
a hydraulic fluid         Heat
dissipation         Ensure optimal coefficient
of friction         Lubrication of transmission
components         Working on extreme high
temparatures         Corrosion
protection         Sealing compatibility       
  Foaming decomposing
 
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4. DEMANDS FOR REDUCING LOSSES PROLONG LIFE OF
TRANSMISSION SYSTEMS     - - REDUCING
THE OIL QUANTITIES   - AGEING
PROPERTIES OF LUBRICANTS   -
APPLICATIONS LUBRICANT FREE OPERATION- DRY
GEARBOXES   - - USE POWDER LUBRICANTS   -
- PROLONGATION OF COMPONENT LIFE  
- OPTIMISING COATING MATERIAL- THICKNESS AND
DEPOSITION MECHANISM -
REQUIREMENT FOR INNOVATIONS   -       
- MINIMUM SIZE OF THE TRANSMISSION -       
- MINIMUM WEIGHT TO POWER RATIO -        
- MAXIMUM RELIABILITY -         -
MINIMUM COST
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5. SHORT DESCRIPTION OF TECHNICAL RESULTS OF THE
RUNNING PROJECTS   5.1 REDUCING THE OIL
QUANTITIES   To minimise the oil quantity a
reduced oil immersion depth was performed in
project TS1. The results showed that the no load
losses decrease with decreasing immersion depths.
But on the other hand the load dependent torque
losses increased with lower immersion depth, in
some cases dramatically. Especially at high
speed of pinion. Figure 1 shows the bulk over
temperature for the pinion at a circumferential
speed of 20 m/s on pitch circle for different
load. Those measured temperatures are in the
range of the tempering temperatures of the case
hardened material.    

Figure 1   The Pitting load
carrying capacity reduced up to 85 and scuffing
load carrying capacity decreased up to 70 for
minimum oil dipping depth.
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5.2 AGEING PROPERTIES OF LUBRICANTS   Some
results of tribological properties of vegetable
oils were investigated in project TS2. The most
promising results of oils in respect to scuffing
and pitting are shown in the Figure 2 and 3. We
expected much more results when start testing in
project TS 10 a TS11.  

Fig. 2. The effect of base oils on the limiting
pressure of seizure poz (steel-steel, four-ball
test)  
Fig. 3. The effect of base oils on
the surface fatigue L10 life (steel-steel,
four-ball test)
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5.3 APPLICATIONS LUBRICANT FREE OPERATION- DRY
GEARBOXES   New concepts of lubrication,
lubrication by a phase transition, were
investigated in the project TS1. Based on the
results of the investigation of literature the
defined coatings consists of low melting alloys,
resinous substances containing solid lubricants
and of wax. The results of tests, on the TS1
project show that coatings could be used within a
limited load and within a limited sliding
distance. On the another hand all investigated
coatings show an improvement of the friction
characteristics compared to uncoated surfaces
under dry lubrication and partly also in oil
lubricated systems.     5.4 USE POWDER
LUBRICANTS   Retardation tests with gears
lubricated with different kinds of PTFE and PE
powder were investigated in project TS1. The
results compared to tests with common
oil-lubricated gears were promising. An
optimised powder Zonyl MP 1600 regarding the
lubrication properties and necessary swirling
behaviour for continuous renewal of the
lubricating film was used, Figure
4..      

Figure 4
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5.5 PROLONGATION OF COMPONENT LIFE-OPTIMISING
COATING MATERIAL     DLC-coatings, thermal spray
coatings and bulk ceramics were investigated in
the project TS1.   The results showed that the
following DLC coatings performed well during
testing and will therefore be used in the future
tests on the gears   1.Diamond like carbon
coatings (Tradename Diamar), consist of Diamond
and Amorphous with 0.11, coefficient of friction
and 6.4 10-8 mm3/Nm wear factor,   2. Amorphous
carbon WC-C (Tradename Balinit C) with 0.15
coefficient of friction and 7.2.10-8 mm3/Nm wear
factor and   3. DLC ( Tradename Balinit DLC) with
0.06 coefficient of friction and 5.1.10-8 mm3/Nm
wear factor.     Application of thermal spray
coatings on gears has to be modified. The bulk
ceramics are not in plan for further
investigation.
  Details are available on the website of the
project!
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In the project TS2 tests were conducted for
selections of thin, hard coating with respect to
mechanical and tribological properties. Some of
the results are shown on the Figure
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Fig. 5. The results of coating characterisation
(load 10 N, sliding velocity 0,1 m/s, debris
removal through draught of dry argon)

a) Wear
rate, b) Friction coefficient   The results
show that single CrN and multilayer WC/C coatings
exhibit good anti-wear properties and lower
friction coefficient compeared to the substrate
and TiN coatings.

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The results shown in Fig. 6 indicate that single
coatings (TiN and CrN) do not exhibit
satisfactory fatigue life. Only WC/C coated
elements has L10 life comparable to uncoated
ones, even higher than achieved for steel
elements lubricated with a mineral oil containing
EP additives, commonly used in gear
oils.       Fig. 6. L10 lives for
uncoated elements lubricated with the mineral
base oil and oil with                        


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The wear volume, wear factor and coefficient of
friction in rolling contact was investigated in
the project TS4.   The tests have been performed
on the CTD-ROL/ Ball-on flat rolling tester under
the following conditions -Non-lubricated -Up to
1 million cycles -Material of flat specimens 100
Cr6 DLC -Ball material 100Cr6 Figure 7 shows
the obtained wear volume and wear factor.  
 

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The effect of surface treatment/texture on the
coefficient of friction has been measured on the
University Halmstad, Sweden. A Large- scale Two
disc machine was used for testing under
lubricated regime and normal load of 225 Mpa.
    As shown there are
the significant differences based on various
surface textures.
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5.6 REQUIREMENT FOR INNOVATIONS-MINIMUM SIZE OF
THE TRANSMISSION For a reduction of the
losses in gears basic changes of gear geometry
have to be done, Figure 11. The investigation has
been done in the project TS1.      
  Optimised gear geometry was designed
with an expected power loss reduction of about
50 for no-load losses and about 80 for load
dependent losses respectively.