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The Prototype Märklin-H0-Knowledge Layout-Building Modelstock |
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A: The very first
basic knowlege about conventionally controlled Märklin H0 model railways A10:
The reverse unit – about leaping,
springs, variants |
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In
this page I say “locomotive” and mean all kind of motorized traction units
too. This
page is preferred for those In
the Märklin H0 system there is no right or left, The
Märklin H0 system works with alternating voltage of 50 Hertz No
orientation whatsoever from which one could deduce a direction, If
you place a locomotive of the Märklin H0 system on the track, it will
continue to run in the same direction as it did on its last run, for example
forwards. To
reverse the direction of travel, to drive backwards, This
switch is the “Remote Control Reversing Gear” The
Reverse Unit is installed invisibly in the locomotive. The
Reverse Unit is an impulse switch It
works in a similar way to a ballpoint pen: How does it work electrically? The
engine and gearbox of the locomotive are designed so that between 4V and 18V is
required to run. This
is the working area of the red rotary knob on the transformer. The
Reverse Unit is designed in such a way that - correctly adjusted - it does
nothing in this voltage range and the direction of travel remains unchanged. But
if you put a current surge with a significantly higher voltage on the track,
namely 24V, by turning the red button to the left beyond zero (or pressing
the button down on an older Märklin transformer or pressing a separate button
on transformers from other manufacturers), then does it, the mechanical
Reverse Unit, *click-rrrrr-click* noticeable. And after that the locomotive
drives in the opposite direction. The
electronic successors of the Reverse Unit are silent. Observable reaction of the locomotive to
the switchover command A locomotive from the time between 1938 and 1957, article no. …800… Sound:
click - rrrrr - click Movement
of the locomotive: none or leap, nothing between. Four
operating modes alternating with each actuation, I
describe and show this Reverse Unit below. A locomotive WITHOUT TELEX couplings, with mechanical Reverse Unit: Sound:
click - rrrrr - click Movement
of the locomotive: none (that would be perfect) to slight. (If
the locomotive races off and continues as long as the changeover command is
pending, we have to look inside ... See below ...) A locomotive WITH TELEX couplings, with mechanical Reverse Unit: Sound:
click - rrrrr - click Movement
of the locomotive: none (that would be perfect) to slight. The
special feature of this Reverse Unit, which has 4 switch positions, becomes
apparent when starting: 1.
After the first switchover from forward travel, the locomotive
continues to drive forward, but the ejectors of the TELEX couplings are
raised. Attached wagons are uncoupled and stay standing still. 2.
When switching over the second time, the ejectors snap up again. The
locomotive then drives backwards normally. 3.
After the third switchover, the locomotive continues to drive
backwards, but the ejectors of the TELEX couplings rise again. 4.
With the fourth switchover, the ejectors snap up again. The locomotive
then moves forward normally. |
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A locomotive with a mechanical Reverse Unit and electronic component: Noise:
click - (very quietly) sssss – click Movement
of the locomotive: none No
adjustment necessary |
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An
incorrectly set mechanical Reverse Unit can cause the locomotive to stop and
hum near top speed. The next time it starts, it may then drive in the
opposite direction. See below for troubleshooting ... |
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A locomotive with an electronic Reverse Unit: Noise:
none Movement
of the locomotive: none No
adjustment possible. |
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High-efficiency motor and electronically controlled propulsion
system: Noise:
none Movement
of the locomotive: none No
adjustment of the reversing function, but of max. speed and acceleration. |
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with DELTA-control or digital control: Noise:
none Movement
of the locomotive: none No
adjustment possible. The
only thing you should pay attention to with this locomotive is that you
operate it with a transformer that is as modern as possible. See page "White
- blue - orange ... transformers between fine and evil". |
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The
mechanical standard Reverse Unit in detail When
Märklin invented the Reverse Unit, no way had yet been devised to keep the
current surge away from the motor. This regularly led to the notorious
leaping. If the locomotive is already running very fast with 18V, with 24V it
goes off like a rocket. One
such original Reverse Unit is shown in the both videos original Reverse Unit, manually
operated This
Reverse Unit has 4 switching positions for 1. parking light, In
the first video I switch it by hand (at that time the locomotives had an
additional hand lever for switching. See also the examples in the picture
with the various locomotives.)
In
the second video I switch electrical. The leaping can be clearly seen. If
the old locomotive does not stop and continue to dash without braking as long
as the changeover contact / button is pressed, it should either be a first
generation Reverse Unit, that does not have a breaker, or the Reverse Unit is
heavily soiled or damaged . More than just adjustment is necessary here. Later
on, contact interruption was developed and "generally" the
lokomotive did not move when switching. Only generally, because the current
is often faster than the mechanical system. Cleanliness and ease of movement
are very important. We
now look at how the mechanics of the Reverse Unit works using the example of
the standard Reverse Unit 20824: (Reference: Märklin-Magazin 2/67 page 24,
bottom left (german)). (Reference:
Instruction
for fitting the Automatic Switch No. 20 824, version 1962) (Reference:
Installation
instructions for Reverse Unit 20824, version 1992). We
have a solenoid and a flap that is magnetically attracted. The
flap moves a slide that lifts a switch plate (the contact break) and turns it
to another contact (the switchover). A
spring pulls the slide and the flap back into the basic position when the
selenoid is switched off again. Now
it is the case that this selenoid, together with the motor, is constantly
connected to the driving voltage. This means that the magnetic force
increases with increasing speed. If
the Reverse Unit is correctly set, the spring force that opposes the
switchover is large enough. that the flap is certainly not tightened at 18V
but only at just under 24V. In
the third video I show the movement of
the Reverse Unit. The
fourth video shows the movement of
the disconnector / switch. Adjustment If
the Reverse Unit is set incorrectly, two alternative malfunctions can be
observed: 1.
Spring too weak: At high speed the locomotive stops and switches over. Remedy: (Warning:
this spring likes to jump off the hook and out of the tweezers, whereupon you
can hardly find it. It's a good idea to have a reserve.) With
a pair of tweezers you can unhook the spring and put it back in with one of
the next turns. 2.
Spring too strong: When switching over, the wheels turn more or less for a
brief moment, the locomotive twitches, jumps, leaps out. Remedy: Use
tweezers to unhook the spring and pull it a few millimeters longer. Then you hang
them up again and try them. The next time you try, you pull a few millimeters
further than the previous time. Fine
adjustment: As
shown in the article in the Märklin
magazine, you can bend the arm to which the spring is attached. Two
brochures are recommended: |
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The TELEX Reverse Unit in detail There
is also a second type of Reverse Unit, namely that for the TELEX coupling.
This was developed in principle from the original form of the Reverse Unit by
adding a separator against the leaping. I
have described the functional sequence above. (Reference:
Instruction
for fitting the No. 21 175 automatic switch, version 1957) In
my 5th video I operate the TELEX
Reverse Unit by hand so that the movements can be seen better. Electrically
operated in the 6th video. You
can also install the Reverse Unit in normal steamlocomotives and switch the
steam generator, for example. |
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The Prototype Märklin-H0-Knowledge Layout-Building Modelstock |
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state: 06.10.2023 20:07 |
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Contact:
Mail |
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