The wahsers of Hatra

In the Mesopotamien Hatra metal parts of the clamping frame and bronze washers with counter plates of one ballista were found. The catapult becomes into the 2nd half of the 3rd Century dated, (D. Baatz, " The torsion catapult of Hatra" see menu option references), it acts thereby around the largest ever found washers. The whole execution shows a highly developed bronze casting technology. The parts exhibit two cast-on reinforcement of the bearing position of the locking- bolts, thus rotation symmetric part of the washers could be implemented thereby at smaller material expenditure.

 


 

Illustration 1
Washer, find from the mesopotamien Hatra. The outside diameter amounts
to 28.5 cm, the inside diameter of 17.5 cm.
Drawing after D. Baatz " The torsion catapult of Hatra"



Arched- strut and torsion stands of Orsava (Romania)




Illustration 2
The two torsion stands with hung up arched-strut. Centre was approx away to
centre torsion stand 1,25 m.
Drawing after D. Baatz and N. Gudea


The arched-strut and the two torsion stands were together found. From the dimensions the parts fit and might have belonged to a catapult. Like the forks of the strut  to the eyes of the torsion stands were tied up is still unsettled.(See also menu option analysis)




Illustration 3
The torsion stand of Orsava in an exploded view.
To better understanding of the constructional
structure in wrong colour representation.


Illustration  3 shows those almost modern working conception of the torsion stand. The upper and lower locking collar is constructionally in such a way trained, that the riveting of the two props does not lie in the sliding surface of the washers  (washers supplements). The retaining eyes were riveted - technically extremely skilfully - with the props at the locking collars. The camp openings for the washers have only one diameter of 80 mm. One draws the centring federation of the washers remains off an inside diameter of the sockets of about 65 mm. A relative small calibre. Again a clear indication for an internal catapult system. The spring volume and thus the inside diameter (calibre) of the washers - without losses of the firing performance - can be clearly reduced by increase the twisting angle with catapult system oscillating inward.



The torsion stand of Sala


This concerns a complete metal design from bronze casting. The lateral retaining eyes are supplemental. The holes for rivets are however identifiable by the original. The eyes might have been from forging iron. Probably these far away by force around the inferior iron from the bronze to separate around those to use by melting further. The whole execution is extremely substantial, laid out for highest demand.


 


Illustration 4
Solid torsion stand as casting. The retaining

eyes are supplemental.


Height of the torsion stand approx. 400m.
Drilling for the clamping chuck (calibre) approx. 80mm.



 


Illustration 5
Three-view drawing. The retaining eyes for the props are supplemental.
Their size and position start themselves however that available rivet holes
reconstruct.

Drawing after Boube-Piccot:
Aiator Iriarte "The In-swing Theory"  

Bobe-Piccot,C: (1994) Les bronzes antiques due Maroc.
IV L'equipment militaire e l'arment, (Paris)



Catapult with roller system

With the representations on the Trajan's Column are shown no catapult arms. Under the menu option analysis was already treated this problem. The idea arose that this bolt-firers possibly none arm systems had. Technically it would be conceivable that instead of the catapult arms roles were put into the rope bundles.





Illustration 6

Hypothetical torsion stand also role in place of a catapult arm.



A role with slots for the torsion bundle and a cast in drilling, poured out of bronze, would be conceivable for the attachment of the chord. An axle for the guidance of the role and an attachment in axial direction  of the torsion stand would not be necessary, since the tautly linked up seeing bundle would fix the role. The chord would be rolled up in the relaxed condition on the roles. With stretching the chord of the roles was completed and the clamping bundles were twisted.




Illustration 7                                                                                       
Hypothetical catapult with one
on roles based catapult system.


After this principle basically - through. M. Böhnisch was simulation-technically examined - the idea was not continued to pursue. Catapult systems with arms are simply significantly more efficient. The advantages " lever performance" the catapult arms does not let itself represent with a roller system simply.