[darwins]

In testing out the OR manual gearbox, I am noticing a number of problems.
First of all variation in engine rpm was very erratic with large increases and decreases in rpm.
This can be partly solved by adding

GearBoxDownGearProportion ( 0.62 )

Although this should only be needed for automatic gearboxes it does calm down some of the variation in engine rpm.

Secondly behaviour in first gear is very strange

https://i.imgur.com/PwGRm0f.jpg

You can see from the above that for some reason unexplained, between 2 mph and 3.5 mph the engine rpm leaps up suddenly and then crashes down again. It is as if an imaginary extra gear had been added with a maximum speed of about 2.4 mph. I would expect to see something more like the dashed green line, depending on how much slippage the clutch will allow.

This erratic behaviour is also noticeable in the tractive force curves

https://i.imgur.com/hQVnC8N.jpg

Another issue is that the maximum speeds for the gears in OR do not correspond to the values entered in the eng file (at least for lower gears and lower speeds).


The eng file entry is

GearBoxMaxSpeedForGears( 4.5mph 6mph 9mph 14.5mph 21mph 33mph )

This is what happens

https://i.imgur.com/FhsO61A.jpg

Gear 1 has maximum speed of 4.8mph instead of 4.5mph, Gear 2 has maximum speed of 7.1mph instead of 6.0 mph, Gear 3 has 9.1mph rather than 9.0mph.
For higher gears and speeds above 10 mph or so, everything seems to work as it should.

[darwins]

I am now trying to find out some more information about mechanical transmissions.

Information about any gearboxes used on railways anywhere would be most welcome.

From what I have found out so far it seems that
( a ) gears were normally engaged anytime the gear/lever (or pre-selector clutch) was in gear, including when the engine was idling, some hydro-mechanical transmissions had a scoop controlled fluid coupling that only engaged above a certain rpm, but so far I have not found any example of this on a purely mechanical transmission;
( b ) there were very few fully automatic mechanical transmissions (as opposed to hydro-mechanical transmissions, most of which are fully automatic or hydraulic transmissions all of which are fully automatic);
( c ) for most mechanical transmissions power is interrupted when gears are changed, for some the driver must close the throttle to reduce the engine rpm when changing up gear, for others the input rpm is automatically braked when a new gear is selected.

Corrections and additions to the following list would be welcomed
https://i.imgur.com/PBI1YRR.jpg

[scottb613]

Hi Darwin,

While not my niche - your attention to detail is very impressive - you are quite the asset around here - IMHO.

Regards,
Scott

[Laci1959]

Quote

c ) for most mechanical transmissions power is interrupted when gears are changed, for some the driver must close the throttle to reduce the engine rpm when changing up gear, for others the input rpm is automatically braked when a new gear is selected.

Such was the gearbox developed by GANZ in the 1930s. There was also a 0 grade between each grade.
0, 1, 0, 2, 0, 3, 0, 4
Between the first gear and the second gear was zero gear, a single notch. He held it there a bit before moving the lever further to the next gear. When switching back, you gave a gas splash to make switching easier.

[Hobo]

That's what they called a " Double Clutch downshift " that was and still is used in commercial vehicles with " Straight cut " gears . Taught in WW 2 to be used on up and downshift by most drivers , especially the inexperenced . It saved a lot of transmission failures .

[darwins]

Laci1959, on 18 October 2021 - 11:35 AM, said:

Such was the gearbox developed by GANZ in the 1930s. There was also a 0 grade between each grade.
0, 1, 0, 2, 0, 3, 0, 4
Between the first gear and the second gear was zero gear, a single notch. He held it there a bit before moving the lever further to the next gear. When switching back, you gave a gas splash to make switching easier.

Thanks for that. I will correct my description of the Ganz gearbox.

Another question is regarding freewheel. As far as I can tell all of the gearboxes that I have described include a freewheel, which allows the train to coast in gear with the engine idling. This is in contrast to the earlier Open Rails algorithm described here Manual gearbox observations

Were there in real life any gear boxes used on railway traction that did not have a freewheel? (That is transmissions where closing the throttle would not reduce the rpm but would instead result in engine braking, the same as a motor car.) Any technical information or links to technical information on such transmissions if they existed would be much appreciated.

[Possibly some simple road vehicle gear boxes were/are used in track inspection cars and maintenance vehicles. I would think it better for these to be a special type in OR rather the default.]

[copperpen]

darwins, on 18 October 2021 - 09:26 PM, said:

Thanks for that. I will correct my description of the Ganz gearbox.

Another question is regarding freewheel. As far as I can tell all of the gearboxes that I have described include a freewheel, which allows the train to coast in gear with the engine idling. This is in contrast to the earlier Open Rails algorithm described here Manual gearbox observations

Were there in real life any gear boxes used on railway traction that did not have a freewheel? (That is transmissions where closing the throttle would not reduce the rpm but would instead result in engine braking, the same as a motor car.) Any technical information or links to technical information on such transmissions if they existed would be much appreciated.

[Possibly some simple road vehicle gear boxes were/are used in track inspection cars and maintenance vehicles. I would think it better for these to be a special type in OR rather the default.]

Far as I can tell, all UK dmu drive systems incorporated a freewheel which prevented the railcar from driving the transmission when coasting. Mechanical drive locomotives used a fluid coupling between the engine and gearbox which served a similar purpose.

[Laci1959]

Quote

Thanks for that. I will correct my description of the Ganz gearbox.

I would rather supplement. I just added.

Quote

[Possibly some simple road vehicle gear boxes were/are used in track inspection cars and maintenance vehicles. I would think it better for these to be a special type in OR rather the default.]

This is still the case today. The engine and gearbox are for trucks. Due to the low number of pieces, it was more economical to use parts from a proven truck type.

[Laci1959]

Quote

That's what they called a " Double Clutch downshift " that was and still is used in commercial vehicles with " Straight cut " gears . Taught in WW 2 to be used on up and downshift by most drivers , especially the inexperenced

When I was a soldier, I was lucky enough to drive one. There was no synchronous ring in the transmission of the Csepel 344 D trucks.
The UAZ 469 also had such a gearbox. I learned to drive a car there.

[darwins]

Just found a nice picture of the Ganz gear control mentioned above.
https://upload.wikimedia.org/wikipedia/commons/8/8f/Arpad_railbus_dashboard.jpg
http://www.elvastower.com/forums/public/style_emoticons/default/smile.gif

[Laci1959]

I found a book and a video about it. There were several types of switches. From manual to fully automatic transmission.
The motor trains shipped to South America had a fully automated transmission (Gear). Electropneumatic. The engine driver only regulated the throttle.
a: disengage the engaged gear
b: release the main switch (coupling?)
c: reduce engine charge to idle (gas take-off)
d: Shift to the next gear
e: gradual closing of the main switch (coupling?)
f: Reset engine charge.
These moments occurred partly over time and partly sequentially. Unfortunately, this is all that has been described about this type.
Sorry, if you have a hard time understanding, google will translate.

[darwins]

Laci1959, on 15 November 2021 - 10:15 AM, said:

I found a book and a video about it. There were several types of switches. From manual to fully automatic transmission.
The motor trains shipped to South America had a fully automated transmission (Gear). Electropneumatic. The engine driver only regulated the throttle.
a: disengage the engaged gear
b: release the main switch (coupling?)
c: reduce engine charge to idle (gas take-off)
d: Shift to the next gear
e: gradual closing of the main switch (coupling?)
f: Reset engine charge.
These moments occurred partly over time and partly sequentially. Unfortunately, this is all that has been described about this type.
Sorry, if you have a hard time understanding, google will translate.

Thank you for that.

This is all very helpful information.

I have another question, I don't know if you can find the answer.

Do the Ganz transmissions used in Hungary include a freewheel?

Also did the Ganz automatic transmissions for Argentina include a freewheel?

(Freewheel allows train to coast in gear.)


...and one more question

Does your video show cab controls at all?

Do the trains with automatic transmission have only Forward-0-Reverse or do they also have Neutral-Drive control?
I have another question, I don't know if you can find the answer.

[Laci1959]

Quote

Do the Ganz transmissions used in Hungary include a freewheel?

There was no express freewheel. In the "0" position between the two gears, the clutch (clutch) separated the motor from the drive. Just like when you roll in the car with the clutch depressed pedal. , Some models had an "X" position between the two gears.

Quote

Also did the Ganz automatic transmissions for Argentina include a freewheel?

Quote

Do the trains with automatic transmission have only Forward-0-Reverse or do they also have Neutral-Drive control?

Unfortunately, I did not find a specific answer. I don't think so. The express request of the Argentine railway was the easy handling after receiving the first specimens, so it was only the throttle that regulated the charging of the diesel engine. The engine driver idled the diesel engine and then braked as needed. According to the description, the Gear Selector Switch initiated the activation or shifting of the appropriate gear at the right time for the speed of the motor vehicle. The Preparing Switch has generated the required electrical pulses to initiate the Grade Selector Switch.
The Pace Switch performed the required actions at the appropriate time.

Allocation of the Harghita multiple unit (DMU?) Gearbox, which is the same as Argentine multiple units:
0 Gear unit switched off
K Standby level. It is likely that this job was used in a position to produce air.
I. 550 l / min, Vmax = 12.2 km / h
I. 1150 l / min Vmax = 25.3 km / h
II. 1150 l / min Vmax = 38.2 km / h
III. 1150 l / min Vmax = 57 km / h
ARC. 900l / min Vmax = 67.5km / h
ARC. 1150 l / min Vmax = 86.1 km / h
ARC. 900 l / min Vmax = 100.2 km / h
V. 1150l / min Vmax = 128km / h

There were two requirements for a multiple unit.
1. Can maintain speed in a given gear.
2. Reach this speed as soon as possible with maximum engine charge.
I. and IV. the allocation obtained by omitting the lower speed version of the gear may correspond to the Argentinian version.
Although this is just an assumption on my part.

[Laci1959]

Reading through what I wrote, I assume that both Argentine multiple units had Off (0) and Standby (K translated S).
However, I could not find out that they could only be switched on when standing still or in motion.

Interestingly, the write engine specified speed (RPM) and speed.
Maybe this should be taken over and applied instead of GearBoxMaxTractiveForceForGears. For compatibility reasons, keep it.

[darwins]

Thanks again. It seems likely from the need for ease of operation and the description about idling the engine and braking as needed that a freewheel would have been present in the automatic transmission.

From an eng file point of view it seems to be

 GearBoxOperation( Automatic )
 GearBoxNumberOfGears( 5 )
 GearBoxMaxSpeedForGears( 25.3kmh 38.2kmh 57kmh 86.1kmh 128kmh )
 
 GearBoxDownGearProportion( 0.66 )

It is very interesting because there were very few automatic purely mechanical transmissions used on trains.

Most automatic transmissions are hydro-mechanical using a torque converter for starting.

Hopefully at some point I will also find some information about the gearboxes produced by Fiat and Tammerfors.