Metal Construction

 
Axial Reciprocating Motor with Link Motion

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  In 1998 we "paused" and built up only a small model:
An axial reciprocating motor with the former available Maerklin magnetic coil, how it is discribed in earlier Maerklin instruction books.

The principle of the axial reciprocating motor (also Page Motor from Charles Grafton Page, 1812 - 1868) is already known since about 1850. With such kind of motor Page wanted to replace the steam power by the electromagnetism, but because of many disadvantages and the at that time insufficient current sources the motor couldnīt be established (further informations one can find in the publication with the title Der Page-Motor, editor: Deutsches Museum).

The operation of an axial reciprocating motor can be compared with a steam engine, but even this works electrical:
An iron core will be magnetized and pulled into a cylindrical coil. By means of a connecting-rod (here named as "working connecting-rod") and an eccentric this motion is converted into a rotation and a flywheel is driven.


If the iron core reaches the center of the coil, the current is switched off and the energy of the flywheel pulls the core out again.
The hereby generated motion sequence is similar to the behaviour of a steam engine.

Picture credits:
Dingler u. a. (Hrsg), Polytechnisches Journal Stuttgart 1846, 102. Bd. Taf. II, Fig. 28.
Axial Reciprocating Motor
Axial Reciprocating Motor


In the Maerklin models an 8 segment collector is used to generate the proper current impulse for the coil. Because this motor has only one rotating direction and one rotating speed, it has been modified in some ways:
Firstly the collector was replaced by a simple spring contact from soft bronze which is activated by a second eccentric and a second connecting-rod (here named as "control connecting-rod"). It is to consider, that the control connecting-rod leads against the working connecting-rod with an angle of 90°; otherwise the motor cannot work.
Furthermore the motor was provided with a link motion, similar to the link motion of a steam locomotive (see also http://de.wikipedia.org/wiki/Steuerung_%28Dampfmaschine%29).



The separated control connecting-rod
The separated
control connecting-rod
For this the control connecting-rod is separated into 2 parts:

The first half (here named as "motion link driving rod") drives a motion link, which is - similar to a steam locomotive - permanent oscillating during operation of the motor.

The motion link itself consists of a Maerklin bow-shaped stripe, whose curved oblong hole works as link track.
In this track the second half of the separated control connecting-rod (here named as "contact driving rod") is vertical shiftable leaded.
The other side of the contact driving rod is supported in a whip, which also acts as the second part of the electrical contact.
The contact
The contact

The contact driving rod in the rotation axis of the motion link
The contact driving rod in the
rotation axis of the motion link
The variation of rotating direction and rotating speed occurs by vertical displacement of the contact driving rod:

If the contact driving rod stands in the rotation axis of the motion link, no horizontal movement proceeds; so the electrical contact is not activated and the motor doesnīt run.


The rotation direction depends on the position of the contact driving rod in the link track:

If it stands in the upper range of the link track the motion link driving rod and the contact driving rod move in the same direction (inphase). Thus the contact is activated and the motor runs in this direction, for which the phase shift of 90° between working connecting-rod and control connecting-rod is effective.

If the contact driving rod stands in the lower range of the link track, the motion link driving rod and the contact driving rod move contrarily (180° dephased). Thus also the electrical contact is activated, but now the phase between working connecting-rod and control connecting-rod is 90° + 180° = 270° and this is equal to 90° for the other rotation direction.



Motion link driving rod and
contact driving rod move inphase
 

Motion link driving rod and
contact driving rod move 180° dephased


The rotation speed depends on the distance the contact driving rod is displaced from the rotation axis of the motion link:

If the contact driving rod stands nearby the rotation axis of the motion link, the horizontal movement is small and the electrical contact is closed only for a short time; the motor runs with a low rotation speed.

If the contact driving rod stands far away from the rotation axis of the motion link, the horizontal movement is larger and the electrical contact is closed for a longer time; the motor runs with a high rotation speed.



The contact driving rod nearby the
rotation axis of the motion link
 

The contact driving rod far away from
the rotation axis of the motion link


Up to now this model is only an object for study without any demand to design.

But altogether because of the lot of movable parts the motor is an impressive model, which is not at all able to drive small models.
The axial reciprocating motor with link motion
The axial reciprocating motor
with link motion


And finally we present a Video of the Axial Reciprocating Motor with Link Motion (120s / 7,17MB).


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