next showmans/roadloco kit. water pump...

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next showmans/roadloco kit. water pump...

Post  craig@STW on Sun 10 Jun 2012, 1:03 pm

the next kit is the water pump. we have started on this but are awaiting materials and the WP castings.

this is the water pump sample casting on the control model (machined and fitted for the recent dutch weekend)...



this is the water pump drive...



cylinder drain lever will be in this kit...



another chance to look at the sample fly-wheel...





gear-change castings. again machined for the dutch weekend and not included in the next kit, but just thought you would like to see them.


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Re: next showmans/roadloco kit. water pump...

Post  Tony King on Sun 10 Jun 2012, 11:19 pm

Great to see more pics Craig........ Thanks!!
Regards,
Tony

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Re: next showmans/roadloco kit. water pump...

Post  Tim Watson on Mon 11 Jun 2012, 4:35 pm

Interesting to see the nylon (?) water pump gear. Should make for a quieter engine, as it's running all the time.

Tim


Last edited by Tim Watson on Tue 12 Jun 2012, 10:09 pm; edited 1 time in total

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Nylon gears

Post  Steve Traill on Tue 12 Jun 2012, 1:20 pm

I noticed what looks like a nylon gear, is this correct? will it cope with the radiant heat of the boiler? Did Burrells fit nylon gears? Does it have a matching nylon gear to mesh with? and will it be strong enough?

As the line in the song goes .........there are more questions than answers.........

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Re: next showmans/roadloco kit. water pump...

Post  Tony King on Tue 12 Jun 2012, 2:44 pm

I wouldn't think heat would be a problem with nylon gear, as it's on the "otherside" of the horn plate from boiler.
Is it to be meshed with a second nylon gear from the crank? Question
Where Burrells infact the first to use this top secret material? Shocked
As Steve T sugests, more questions than answers!! Very Happy
Regards,
Tony

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Re: next showmans/roadloco kit. water pump...

Post  Tim Watson on Tue 12 Jun 2012, 10:10 pm

Wouldn't you want it meshed against a steel gear on the crank?

Tim

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Gear wheels

Post  Steve Traill on Wed 13 Jun 2012, 12:20 am

I seem to remember reading somewhere that gear wheels should be of a similar material otherwise one will 'pick up' material from another, could be wrong but when looking at the inner workings of anything with cog wheels they tend to be all the same material.

The flywheel is looking great as are the gear lever castings, just puzzled over the nylon gear wheel!! Nylon was invented on February 28th 1935 by Wallace Caruthers of DuPont.

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Re: next showmans/roadloco kit. water pump...

Post  Steam Traction World on Wed 13 Jun 2012, 12:25 am

Hi,

It meshes against a steel gear on the crank and was done in an oil impregnated nylon to reduce the noise of the water pump drive. As the gear is basically inside the flywheel, the flywheel acts as a bell surround amplifying everything.

Dean


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Re: next showmans/roadloco kit. water pump...

Post  Steve Traill on Wed 13 Jun 2012, 1:12 am

Just googled plastic gears & I'm completely wrong on similar materials being best for gears, here's some stuff that might be of interest re the nylon gears.

Engineering Principles for Plastic Gears

In many instances, plastic materials perform markedly better than do metals--especially in gears. Read on to learn the details that will allow you to make the best choice for your operation.
By: Rudy Walter


Download PDF

Since founding Timco in 1967, I've been riding a steep learning curve regarding plastic materials and the machine parts that we make from engineered plastics. Just when I thought that this strenuous curve was about to level off due to my retirement, my colleagues asked me to write about machined plastic gears. I hope this information will be useful to you.

The following is written for metric gear calculations, and some of the metric terminology has been retained. As an example, the term "modul" can be equated with "diametrical pitch."

Plastic Materials
Properly selected plastic materials offer better performance than metals when all or some of the following requirements must be satisfied:

•Low maintenance

•Wear resistance when running dry

•Low noise

•Vibration dampening

•Corrosion-proof

•Low inertia due to low rotating mass, light weight

•Low manufacturing cost

Polyamides can be engineered toward one or more requirements, as is shown by the following listing of the plastic materials most commonly used for manufacturing gears:


1) PA 6 (Polyamide 6): this material is wear resistant and absorbs impact even under rough conditions, but it is less suitable for small precision gears.
2) PA 66 (Polyamide 66): compared to PA 6, this extruded polyamide offers better wear resistance (except against mating surfaces of high quality), absorbs less moisture and is dimensionally more stable, but it is also less suitable for small precision gears. 3) PA 6 G (Cast Polyamide 6): the high degree of crystallization makes PA 6 G especially wear resistant.
4) Calaumid 612/612-FeĆ (cast PA 6/12): this polyamide is engineered toward toughness against shock loads, with wear resistance similar to PA 6 G. (Calaumid is a Timco exclusive)
5) Calaumid 1200/1200-FeĆ (cast PA 12): a lower degree of moisture absorption gives better dimensional stability. It has excellent wear resistance and withstands high shock loads.
6) PA 6 G + Oil (Cast Polyamide 6 + Oil): the addition of lubricating oil into the PA 6 G provides very good dry running and wear resistant properties.
7) POM-C (Polyacetal-C): this Acetal absorbs very little moisture, which makes it suitable for precision gears, but it needs continuous lubrication under high loads.
Cool UHMW-PE (ultra-high molecular weight polyethylene): PE absorbs no moisture, is dimensionally stable, resistant against chemicals, and dampens vibrations, but it is suitable only for low loads.

There are limitations of speed and load for plastic gears, of course. Metal gears usually operate well within the temperature limits of the material. The design of plastic gears, however, must always take into consideration the increase in temperature which is caused by friction, pressure, and speed. The following paragraphs will show how one's design can safely stay within these limits.

Quality of Mating Gear:
The gear which mates with a plastic gear can also be of plastic, but only in slow and lightly loaded applications. Otherwise, case-hardened steel is the best mating material because it dissipates friction heat quickly. The harder the steel, the slower the wear on the gear wheel and pinion. We recommend a surface quality of Rt = 8 to 10 µm, both for dry and lubricated applications.

The driving pinion is always subject to greater wear, therefore the pinion should always be of the more wear resistant material (e.g., steel pinion/plastic gear wheel; PA pinion/ POM gear wheel).

Lubrication:
Automatic lubrication will improve the break-in performance and the overall lifetime considerably. Plastics which are engineered with oil additivesăsuch as PA 6 G + Oilăprovide much longer lifetimes than all other plastics. Continuous oil lubrication results in better friction heat dissipation and longer useful lifetime, or higher load bearing capacity. With grease lubrication, the circumferential speed should not be higher than 5 m/sec so that the gear does not sling off the grease. We do not recommend that you lubricate polyamides with water because the material tends to absorb water.

Noise Generation:
The excellent noise dampening properties of plastics result in a quieter-running gear. The graph below shows noise generation in dB of steel against steel "a" and of steel against plastic "b" at increasing speeds. The difference is as much as 9 dB. Steel against steel generates up to three times as much noise than does steel against plastic. Noise equals wear: When we replaced the noisy steel pinion gears in the drying section of a paper mill with PA6G gears, the noise disappeared, and one could stand a nickel upright on the housing of the running gear.


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Re: next showmans/roadloco kit. water pump...

Post  mikero on Wed 13 Jun 2012, 2:00 am

Thats us told. Smile

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Re: next showmans/roadloco kit. water pump...

Post  Tim Watson on Wed 13 Jun 2012, 2:24 am

Like I said.

Tim

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Plastic gears!!

Post  Tony King on Wed 13 Jun 2012, 2:53 am

I found this thread very interesting & it looks like STW have made a very good decision with the nylon gear pump drive........ I knew that!! Very Happy
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Tony

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using nylon

Post  Watts&Son on Wed 13 Jun 2012, 1:28 pm

A friend of mine is considering using replacement main bearings on his full size burrell steam roller, using nylon, I have been told there are engines using nylon on the bearings for the back axle, must be loading 10 tones at least.

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Re: next showmans/roadloco kit. water pump...

Post  Robfishman on Wed 13 Jun 2012, 3:55 pm

Is very interesting. Of course back in the day there were instances where you deffinately didn't want steel on steel gears, as they can produce sparks and FIRE. Such as in milling machinery where steel and timber was used. It's also meant if something went wrong you would break the cheaper timber tooth and not the cast iron gears and rings.

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Re: next showmans/roadloco kit. water pump...

Post  Tim Pennett on Wed 13 Jun 2012, 4:33 pm

My understanding for the use of a Nylon Gear for the Pump (in models) was that water is more difficult to compress in the pumping action; therefore, if there was to be a jam/blockage in the flow of water (at scale), it would be the gear that shears rather than causing any further damage by spraining the pump ram arm, motion etc at relatively high crank speeds.

Despite the down gearing from the main crankshaft there is the potential for this to happen on Road/Showman’s Engine which would run at a higher rmp than Agricultural Engines hence why some full size Road Loco’s were fitted with two injectors rather than a pump.

Although I must admit Steve’s explanation seems far more informative!

Tim

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Gear wheel

Post  Steve Traill on Thu 14 Jun 2012, 12:22 am

Hi Tim
That's a very good point as I've seen what can happen when you try & compress water! Metal bends instead! I won't mention any names but I know someone who had closed the clack valve on the side of the boiler for maintenance & forgot to open it again. Steamed the engine, was driving along & thought I'll pump a bit of water in, within seconds he had a bent hornplate & a trashed pump connecting rod! So having a deliberate 'weak link' sounds like a good idea.

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Re: next showmans/roadloco kit. water pump...

Post  Flasback on Thu 14 Jun 2012, 9:04 am

check question, when will this kit be sent out, sorry to ask Embarassed

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Re: next showmans/roadloco kit. water pump...

Post  craig@STW on Sun 17 Jun 2012, 1:19 pm

more work done on this kit...

the material for the water pump eccentric straps is being blocked out (cast iron is available in limited sizes)...



and the eccentric strap pins are done...



the straps will be made in two halves and then bolted together for the centre bore to be done.

water lifter rose/ends being assembled...


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Re: next showmans/roadloco kit. water pump...

Post  Robfishman on Sun 17 Jun 2012, 2:15 pm

Thanks for the updates Craig, it's great to see the work behind the scenes.

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Re: next showmans/roadloco kit. water pump...

Post  bjwlancashire on Thu 21 Jun 2012, 12:51 pm

Steve did confirm to me the other day that the water pump is this month's kit and for those of you steaming up already (and your neighbours), the pressure gauge is coming too Shocked

Brian

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Re: next showmans/roadloco kit. water pump...

Post  craig@STW on Sun 24 Jun 2012, 1:22 pm

more progress on the water pump eccentric straps...


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Re: next showmans/roadloco kit. water pump...

Post  Tony King on Sun 24 Jun 2012, 1:35 pm

"Oooooooooh" !! that looks like alot of machineing on those solid blocks!!
Looks very nice Very Happy
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Tony

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Re: next showmans/roadloco kit. water pump...

Post  highpressure on Sun 24 Jun 2012, 2:24 pm

Have you got an idea of how soon this is before it will be ready to go??

Cheers Kev.

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Re: next showmans/roadloco kit. water pump...

Post  lynnr on Mon 02 Jul 2012, 3:33 am

Hello world.. Gone very quiet? is there anyone still out there?

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Re: next showmans/roadloco kit. water pump...

Post  Dan on Mon 02 Jul 2012, 4:56 am

lynnr wrote:Hello world.. Gone very quiet? is there anyone still out there?

I think Isabel is on holiday - hence I just got a call from Dean saying Kit 9 was heading my way - I think they are a tad busy!!! Laughing

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Re: next showmans/roadloco kit. water pump...

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