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Messages - TerryM

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1
Changfa Engines / Re: Weichai 1115, 25hp Changfa-type
« on: April 22, 2007, 04:18:19 AM »
Steve - Thanks for the update, but now I'm really puzzled.  Let's put aside the original issue of an abnormally high output power from the Lister and discuss what appears to be a safety issue.  I'm going to try to do some text-based schematics to illustrate the important points. 

Standard wiring for a house has a 240 VAC feed coming from the pole or underground transformer in the form of two 120 volt circuits with a common neutral (sometimes referred to as a " return") running 180 degrees out of phase with one another.  The 180 degree phase relationship is what causes the hot-to-hot line voltage to be 240 VAC instead of zero.   In your house, you have 240 VAC appliances (dryer, stove, hot water heater) and 120 VAC appliances (TV, computer, refrigerator, etc.).  The 240 VAC loads are connected across the two hot lines "phase to phase" while the 120 VAC loads are connected from one phase to neutral - effectively ground.  Like this:


   Hot-1     >----------------------------------------------------------------------------------      <---
                         |                 |              |            |                                      |
                     120 VAC             120 v applicances                                         |
                         |                 |              |            |                                      |
   Neutral   >---------------------------------------------------------                              240 VAC Appliances
                          |                 |              |            |                                      |
                     120 VAC             120 v applicances                                          |
                         |                 |              |            |                                       |
   Hot-2     >----------------------------------------------------------------------------------     <---

One of the features of this configuration is that regardless of the current drawn by the 120 Volt appliances, they
only see 120 VAC (subject to minor fluctuations in the input power).  Now lets look at your wiring configuration:

 Hot-1     >----------------------------------------------------------------------------------      <---
                         |                 |              |            |                                      |
                     ??? VAC             120 v applicances                                          |
                         |                 |              |            |                                      |
                         |                 |              |            |                              240 VAC Appliances
                         |                 |              |            |                                      |
                     ??? VAC             120 v applicances                                          |
                         |                 |              |            |                                      |
   Hot-2     >----------------------------------------------------------------------------------     <---


The 120 volt applicances are now connected in a series configuration and the voltage drop across each one is dependant upon
the load that each one draws.  In other words, if you had a light load in series with a heavy load, the voltage drop would become
unbalanced.  For instance, you could see 150 VAC across one of the appliances and 90 VAC across the other.  This is bad electrical
karma.

If the wiring from the generator is as you believe it to be (i.e. no neutral), you have a very hazardous condition with the potential to subject motors, lights, computers, TVs, etc to voltages well outside their design specs .  I'm surprised you haven't seen flickering lights, refrigerator motors groaning as they start and other anomalous conditions.  My advice to you is to put the generator testing with your house on hold until you can get a gen head with a neutral for 120/240 VAC operation. 

Terry



2
Changfa Engines / Re: Weichai 1115, 25hp Changfa-type
« on: April 21, 2007, 03:28:14 AM »
Since Biloxibad lives in the SE US, I presume that his 250 volt generator output is actually split into two 125 volt circuits with a common return.  With one ammeter, he has to be measuring one of the two hot legs, so the only thing that can be concluded is that the generator is powering a load of 125 V RMS x 29 amps = 3.625 KVA on one of the two 125 volt circuits.  Depending upon how much of that load is inductive (e.g. AC motor), the power factor could be 0.8 - 0.9 which would make the real component of the load on that leg 2.9 KW - 3.26 KW.

Since the current on the other hot leg is not being metered, there is no way to determine the total load on the generator.  My suspicion is that Biloxibad is running his AC unit on one leg and a bunch of lights on the other such that there is a fair amount of imbalance.  This would explain the seemingly extraordinary power output  from a 6 HP engine.

Biloxibad, if you're interested in accurately determining the output power of your generator, you have to put a fairly steady load on both circuits and measure the current draw in both hot legs.  Multiply each current times the voltage measured from the corresponding hot side to neutral and sum the values.  For example, assume you measured the following voltages and currents:

Hot side 1 to neutral = 120 volts
Hot side 1 current = 30 amps

Hot side 2 to neutral = 125 volts
Hot side 2 current = 10 amps

For simplicity assume that the loads are purely resistive so the PF is unity.

120 x 30 = 3600 watts
125 x 10 = 1250 watts
                 ========
                 4850 watts

Terry


3
Thanks for your comments, Chris.  I've viewed your videos on several occasions with head phones on trying to determine if your engine exhibited the same mechanical noises as my 1115. On my computer, there isn't a dramatic difference in the level of exhaust noise on the two engines - I suspect that whatever video device you were using  has some sort of automatic gain control or limiting to prevent the audio from exceeding a fixed limit.  Over a period of time, I've come to the conclusion that Changfa's are kinda like a Detroit Diesel - it's normal for them to make lots of mechanical noise.  Your post corroborates that view.

 I've also got a Changfa R185 which I have yet to put a load on.  In general an unloaded 1115 is significantly louder (est ~ 10 dB) than an unloaded 185, while a loaded 1115 is dramatically louder.  Loud as in when I walk out into the street with the engine running  in the garage, it's necessary to travel  well down the street to be able to carry on a conversation without lip-to-ear shouting.  I just purchased the muffler from H*LL from a surplus supplier called Groban out of Chicago.  Their muffler page can be found here:   http://www.groban.com/mufflers_silencers_36.html).

 Here's the description for the one I purchased (third from the top on the extreme left of the page):

Model BMAL-3, P/N 512755-26, Code AP-9-84,
2" side inlet, 3" end outlet, pipe thread,
Welded Steel Construction, with drain plug.
Overall dim: 42" L x 10" D. Shipping Wt. 42 lbs.

It's a Burgess Manning industrial muffler that the manufacturer claims 20 - 35 dB of sound reduction.  I've got great hopes that this will knock the exhaust level down so that it is no longer the dominant contributor.  Right after that, I intend to fit some sort of silencer on the intake to quiet the repetitive WHOOMP-WHOOMP-WHOOMP  that is nearly as loud as the exhaust.  As I recall, you fitted a Solberg to your R185.  How effective did you find that to be and did you have any difficulty adapting the silencer to your intake manifold?

Terry

4
Generators / Re: ST 5 Arrives
« on: April 10, 2007, 02:29:02 AM »
Doug, I'm not (much of) a welder either, but I think MIG welding or MIG brazing might be a solution.  Check this out:

http://www.mig-welding.co.uk/cast-iron.htm


Good Luck

Terry

5
Other Slow Speed Diesels / Re: question about changfa style engine
« on: April 10, 2007, 02:19:42 AM »
Michael,

The component you've circled is an installation aid that depresses the piston in the injection pump so it will clear the cam lobe when you R & R the front case cover.  Scroll down to my post ""Acceptable Slop in Crank to Balance Shaft..." and look at the second image.  It's a shot of the backside of the front case cover.  The cover is upside down so the injection pump is in the upper left hand corner.  You can see the back side of the circled component behind the injection pump.  Scroll down to the next photo and you can see the location of the injection pump cam lobe in the lower left corner.

The way the installation aid works is that half the shaft is removed for the last 15 mm or so, such that if you looked end-on at the shaft, it would appear like the letter "D" - flat on one side and rounded on the other.  The operational position is with the flat towards the injection pump piston.  During reassembly, you turn the nut on the outside of the case and the "D part of the shaft rotates until the rounded part bears on the piston and depresses it just enough to clear the cam lobe.  One you get the case cover on and secured with a couple of bolts, you rotate the nut until you feel it lose contact from the piston. 

Congratulations your Changfa acquistion - you're going to have a lot of fun with it.   They're hellishly loud and sound like they are going to come apart at any moment.  It's taken me a while to realize that Changfa noise is a lot like Detroit Diesel noise - that's just a characteristic of the machine and isn't indicative of imminent failure. 

Cheers,
Terry

6
Generators / Re: Harbour freight gen heads
« on: April 05, 2007, 04:14:43 AM »
Snutr, I'm not your best resource when it comes to slow-speed diesels like the lister.  I think you may have some flat belt options with that engine that I'm just not very knowledgeable about. 

If it does turn out that you have to fit the engine with a new sheave, you can find a wide array of v-belt and synchronous sheaves at Applied Industrial.  They carry a variety of brands, but seem to push Martin Sprocket and Gear components pretty hard.  The Martin website has an absolutely excellent set of design guides that will walk you through the process of selecting the right sized sheave and belt that can handle the power you're using.

Terry

7
Generators / Re: Harbour freight gen heads
« on: April 05, 2007, 01:46:18 AM »
If you're looking for an alternative to an ST head, check out the "Blaster Wholesale" website located here:  http://blastwholesa1le.com/products.php?cat=11.

They are offering two models of 2-bearing generators with shafts set up for belt drive - one is 5 KW and the other is 7.2 KW - both 3600 RPM.  Pricing is $350 and $400 respectively.  I think that Blaster is a one-man outfit, but he filled my order promptly and answered the phone when I called to inquire about shipping status. 

These generators are made by Mecc Alte Spa which is an Italian company.   I purchased the 7.2 KW unit which carries a 7800 VA continuous rating on the label plate with a 10% overload allowed for 1or 2 hours out of 24.  I'm driving mine with a Changfa-style 1115 using a H100 synchronous belt.  Whatever noise the generator makes is completely swamped by the racket from the engine. 

So far I've briefly loaded it to 7 KW and put a 4.5 KW load on it for half-an hour or so.  The generator case was never more than slightly warm to the touch - I'd guess 100 degrees F or so.  One noteworthy aspect of this generator is the voltage regulation.  No load to 4.5 KW causes the output voltage to sag only a volt or two.  It's a brushless design, and I think that it somehow uses current drawn from the armature to add to the excitation of the field.  I haven't been able to locate a good description of the theory of operation, but it works very well.

One thing that is important to keep in mind is that a 3600 RPM generator is more difficult to drive than an 1800 RPM unit using a medium speed diesel like a Changfa (I assume that this is even more true with slow speed diesels).   With the dinky little 5" or 6" sheave that comes with a Chanfga-style engine, you need to use a 2 1/2" or 3" sheave to get the 2:1 drive ratio required by the generator.  Those kinds of diameters violate the minimums recommended by sheave manufacturer's like Martin and Maurey, plus you've got to use 4 B sized v-belts with a lot of tension to handle the power.  Most 3600 RPM gen heads aren't built for a lot of side load on the shaft, so bearing life isn't apt to be real good.  Purchasing a larger 4 groove sheave (8" - 10" dia) for the engine shaft along with the bushing can easily run over $200 by the time you include the belts.  I like my Mecc Alte gen head, but the next one I buy will be an 1800 RPM unit.

Terry

8
That's diesel knock you're hearing, Phil - absolutely normal and nothing to worry about.  You'll find the knock to be particularly pronounced when the engine is at low speed and you advance the throttle.  As soon as your hearing rolls off by 20 dB or so, it won't bother you a bit...

Terry

9
Glad you liked the photos, RM.  There doesn't seem to be a whole lot of Changfa disassembly/reassembly info on the Internet, so I wanted to share the details with other owners who might have to do something similar.

My other motivation was to show off the elegantly simple Changfa design  On this forum, Changfa engines are viewed as sort of cross between Rodney Dangerfield and that triumph of Serbian technology, the Yugo - not held in real high esteem.  It seems to me that the Changfa's shortcoming notwithstanding (brain numbing noise level and vibration sufficient to shake your fillings out), the engine's ease of repair is worthy of at least grudging respect.

With regard to the moly disulphide, I've read about it but don't have any direct experience.  Do you have any specific recommendations as far as an appropriate quantity for a 3 ltr sump?

Cheers,
Terry

10
Thanks, MJN - I suspected that this was a design issue common to at least the larger sized Changfa-style engines, but it helps to get some confirmation. 

Yesterday, I went ahead and, with more than a little anxiety, pulled the front cover of the engine so I could inspect the gears.  Here's a little photographic record of that operation.

The front cover is designed with an integral injection pump, so the only thing you have to do is break the fuel lines to it, remove about 9 bolts and pull the cover, injector, and internal governor linkage off as a single assembly.  You'll want to have a pan underneath so you can catch the oil and the ball bearings that will fall out of the governor.  Here's what the gear train with the governor "bowl" in place looks like.



This is a shot of the backside of the front cover - pretty simple, eh?




Here's the gear train with the governor bowl removed.  The slots around the periphery hold one ball bearing each.  As the governor gear spins faster, the bearings move furthor out toward the periphery and that pushes the bowl out towards the front of the engine.  You can see in the second photo that there is a large fork that rides on the bowl - this is the governor linkage. 

The small gears in the upper right and lower right of the engine are connected to the counter-balance shafts.  One is driven off the governor gear and the other is driven by the manual crank gear - both of these acting as idler gears.  The cool thing is that all of the gears have numbers stamped on the teeth that allow you to accurately line everything up.  For example, there is a "0" on one gear tooth, and the mating gear has two "0" on adjacent teeth.  When identical numbers are lined up on all the gears, everything  synced.  As I recall, there are two sets of zeros and then "1" - "3".  This proved to be an incredibly useful feature because in the process of removing the cover, one of the idler gears pulled out far enough to disengage the upper right counter-balance gear.  The counter-balance promptly rotated out of sync as gravity acted on the balance weight.  Without the numbering scheme, I would have been well and truly screwed.  With it, it took about five minutes to get all the gears synced up again. 

I did a careful inspection of the counter-balance gears and discovered the source of the "klunk".  While the teeth are well engaged, there's about 0.015" of slop in the gears.  John Alvin of Power-Co.Net told me that a diesel manufactured in this country would have about 0.005" of gear lash.  I couldn't find anything that would explain the excessive clearance beyond being designed that way.  The gear teeth showed no signs of wear - every tool mark of the original crappy Chinese machining was still visible (although it's worth noting that the engine only has ten hours or so of lightliy loaded operating time on it.



This last image shows a cheap and dirty way to keep the governor bearings in place while you put the bowl back on - pack the slots with grease!



Reassembly was straight forward.  The funny looking fixture on the front of the cover that looks like a circular cover secured by a screw with a nut in the middle of it is used to depress the plunger of the injector pump so that it will clear the lobe of the injection pump cam.  All in all, this is a really slick design that is incredibly easy to work on.

After bleeding the injectors, the engine started right up and I put a 4.5 KW load on it after it was warm.  With the engine loaded, the gear noise from the counter-balance shafts went up markedly - load off, and the gear noise subsides.  I think the noise is the sound of gear teeth banging into one another - first the leading edge, then the trailing edge.  This seems like it would ultimately lead to premature wear or failure of the gears, but maybe the gears are hard enough to withstand the abuse for an extended period of time.  I think I'll be pulling the front cover again at 1000 hours or so to see how they are fairing.


Terry

11
Based on comments from posts in another thread, I came to the conclusion that my Changfa-style 1115 might have a significantly higher level of vibration than what other owners were seeing with equivalent or larger engines.  Shortly after that, I noticed that when the flywheel was rocked back and forth through a 15 - 20 degree arc, there was a noticeable "clunk" from inside the crankcase.  Initially, I though I had a bad rod bearing, but after removing the piston and connecting rod, the noise was finally localized to the gears that connect the crank to the balance shafts. 

When the engine is running, I don't hear anything that would suggest that the engine is coming apart, although with a stethoscope, I think I can hear a light "clunk" occurring at the same speed or a sub-multiple of the crank speed. 

I'd like to ask other owners of 1115's or 1125's to run a 30 second test on their non-running engines.  Could you please roll the flywheel to a point away from the compression stroke, rock it back and forth through a 20 degree arc, and let me know what you hear in terms of mechanical noises from the crankcase?

Thanks guys,

Terry

12
Other Slow Speed Diesels / Re: Kubota Engines Manufactured by Changfa?
« on: March 27, 2007, 02:40:36 AM »
Quote
The genset is simply sitting on the plywood, no anchors and has had no tendancy to walk , creep or crawl at all.


Wow, that's kind of disconcerting since it supports  Mobile_Bob's suggestion that I've got a counterbalance weight out of sync with the piston.  A complete tear down at this point in the engine's life isn't something I'm looking forward to.

Steve, I'm having trouble reconciling the failures you discussed in your earlier post that seem to be vibration related vs. the stability you report in this most recent post.  Is the I-beam frame the engine is mounted on fairly heavy?

Can any other 1115 owners chime in with their experiences with their engines tending to walk when not firmly attached to something heavy?

Terry

13
Other Slow Speed Diesels / Re: 1000 hours on a changfa style engine
« on: March 27, 2007, 02:27:46 AM »
You might also try Carrol Stream Motors - you can find their contact info at:  http://www.carrollstream.net/

Terry

14
Other Slow Speed Diesels / Re: Kubota Engines Manufactured by Changfa?
« on: March 25, 2007, 08:22:57 PM »
RE Mobile_Bob's suggestion to check the timing of the counterbalance - RCAVictim (where do you guys get these handles?) suggested that I pull the sump cover off a while back and get some photos of the interior so he could compare the appearance with that of his Changfa.  I did that and posted them in a thread titled "Manufacturer of Carrol Stream Motors Single-Cyl Horizontal Diesel".  What struck me at the time that I was taking the photos is that the cut-out in the counterbalance exactly matched the shape of the rod end and they seemed to be synchronized - i.e. at the point in time that the piston was at BDC, the cut-outs were just missing the rod end.  I'm struggling a little with the explanation, but the photos posted on the other thread illustrate the point.  I suppose that they could have been a tooth or two off and I wouldn't have noticed.  Has anyone had any experience checking the relative timing of the counterbalance with the crank and can it be done without stripping the engine down to parade-rest?

Steve - Interesting to hear your experiences with an even bigger animal than the 1115.  It was pretty clear from your comments that the engine has a serious vibration issue, but you didn't say anything about its propensity to walk around when unrestrained.  Could you comment on that and also provide a brief description of the frame you've got the engine mounted on? 

Touching briefly on the topic of reducing the dB level of these engines, I've been mulling over some ideas that I'll post in a separate thread.  On the exhaust side, the hard part as I see it is figuring out how to mount the muffler so that (1) you don't have a long springy structure that destroys itself from vibration, (2) doesn't significantly increase the footprint of the gen set, and (3) doesn't require the muffler to be tucked into a space that would be better utilized for another function such as a radiator or a fuel tank.  So far, I've been designing my genset on the basis of "TLAR" (that looks about right) and I find myself routinely having to back up and change the design to work around some problem I didn't anticipate.  It sounds like N9ZES has been down this path as well as several others, so I'm hoping to get enough tips to get the design right the first time.

Cheers,
Terry

15
Other Slow Speed Diesels / Re: Kubota Engines Manufactured by Changfa?
« on: March 25, 2007, 04:23:23 PM »
Thanks for all the comments and suggestions, guys.  This thread is rapidly diverging in three more or less orthogonal directions:  origins of the Changfa-style engines, their tendency to "walk", and silencing.  I'm going to set the silencing topic aside for the time being - this is a topic of intense interest to me and it deserves its own thread.

With regard to Fattywagonman's comments, I can certainly see some design features of the 43E and 43F (particularly the latter) in the Changfa.  I wonder if what we're seeing here is evolution turned on its head  as the rather sophisticated German design is knocked off by the Japanese, and then further dumbed-down by the Chinese.

With regard to the "walking" of the 1115, I also have a Changfa 185 which is a sweet little engine.  I haven't even gotten if off the packing crate base, but it's reasonably stable even with one securing bolt missing.  The 1115 is another story.  This thing is just an animal  - they're *much* bigger than they look in photos you see online.  To quote Jim Lerch, who has an excellent web page of his Changfa project, "My GOD, It's a HUGE 1.2L single cylinder diesel engine!


 I've got mine mounted on skids made of two 4x6's with angle iron bridging the two - the engine bolts to the angle iron.   The first time I fired it up, it happliy did a slow motion waltz around the garage,dragging a 100 AH battery behind it.  I then built "shoes" with inner-tube rubber glued to the bottom that slid on the ends of each of the skids - that was a little better.  Yesterday, I mounted an additional 150 lbs or so of adapters, busihings, sheaves and generator on the base and that seemed to do the trick provided I had the skids aligned with the slope of the garage floor.

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