Leonardo Da Vinci’s Self-Powered Cart — South East London Meccano Membership
Determine 1 Preliminary Meccano mannequin of Da Vinci’s self-powered cart
Background
In June 2016 I used to be requested to provide a presentation and demonstration of Meccano to a category of kids at Charlton Church of England Main College in Dover, who had been in search of inspiration for an in-class building challenge.
As classroom area was restricted I used my M4 High-Speed Tractor because the bodily demonstrator and confirmed a 50+ PowerPoint slide presentation to cowl the origins of Meccano, typical fashions from easy to extra complicated, and to point the vary and variety of material potential in Meccano modelling. This was very properly obtained by an attentive and class.
An end result of this occasion was that I used to be invited to assist supervise a gaggle of the category on a go to to Dover Transport Museum. After recovering from the truth that I had by no means heard of this venue, on researching it I used to be amazed to find the vary of automobiles and memorabilia on show there!
On the day of the go to, while the kids had been being mustered and instructed how one can behave in the course of the go to, I had time for a preview of the museum. To my additional amazement, within the lobby was displayed a big reproduction of Da Vinci’s self-powered chariot (determine 2). The car is about 2m sq., and is constructed in wooden of fairly large proportions. One of many museum employees proved to be conversant with its working and gave me a reputable rationalization of the way it was powered by the leaf springs related to capstans driving the wheels. He had seen it function on just one event when it travelled about 20 toes underneath its personal energy.
Determine 2 An interpretation of Da Vinci’s self-powered cart in Dover Transport Museum
I consider the picket model on show had been produced by a college group some years in the past, who claimed it to be their interpretation of Da Vinci’s well-known sketch. It had been found in considered one of many buildings beforehand owned by the Ministry of Defence which was now utilized by the museum.
All this was a whole revelation to me as, over time, I had studied Da Vinci’s sketch (determine 3) on a number of events, within the hope of reproducing it in Meccano at some point, solely to surrender in despair of deciphering its working from the drawings, an end result that many earlier than me had additionally suffered apparently.
Determine 3 Da Vinci’s sketch, circa 1478
Additional Analysis
The web revealed some attention-grabbing outcomes — over the centuries, many students have puzzled over Da Vinci’s sketch, most of whom assumed that the motive energy was offered by leaf springs. This concept was questioned in 1975 by Carlo Pedretti (see reference 1) who proposed that the springs proven in Da Vinci’s sketch weren’t a part of the drive system.
In 1996, Mark Rosheim wrote in a guide that he thought that the ‘automobile’s engines’ had been coil springs situated in tambours (drums) on the underside of the cart. This led to Professor Paulo Galluzzi, director of the Museo Galileo (previously the Institute and Museum of the Historical past of Science) in Florence, Italy, commissioning a 3D CAD digital modelling challenge in 2004 (see reference 2). Movies of the particular and digital cart present a superb perception to the machine. The challenge realised full-size and one-third scale fashions of the cart, the latter being demonstrated in Florence in April 2004 (determine 4).
The museum referred to the machine as ‘Leonardo’s vehicle’, implying it was the primary automobile.
Determine 4 Working mannequin of Da Vinci’s self-propelled cart — notice the divided axle!
The Brake
As indicated in Da Vinci’s sketch, the machine is provided with a brake that jambs between the tambour gears. This may be launched by a rope permitting the machine to be set in movement by an operator hiding out of sight, thereby including to the mystique.
Escapements
On the high of every vertical drive shaft pushed by the tambour gears are rimless spoked wheels into which gentle leaf springs interact to carry out a velocity regulating operate.
Programmable Steering
It transpires that the leaf springs, initially thought to offer traction, had been a part of the steering system. The gears above every tambour are fitted with a variable variety of cams which function arms, the other ends of that are connected to the aforementioned leaf springs. One in all these arms is secured to the smaller wheel vertical shaft, thereby turning (steering) the wheel in response to the cam motion.
The system signifies that the machine can solely steer in a single route, until the cams are rearranged.
The variety of cams employed permits one or a number of steering actions per revolution of the massive gears to which they’re fastened, therefore the time period ‘programmable steering’.
Rigidity adjustment of the arm activating the steer movement is by a rack and pinion association — this has led to a proposal that Da Vinci invented the rack and pinion steering mechanism.
A Query
After a lot research and repeated viewing of movies and different references on the topic, I used to be nonetheless uncertain as to how these fashions truly labored. My dilemma was understanding how the machine may steer, when the 2 gears above the tambours are meshed collectively. This association signifies that each driving wheels are instantly geared collectively, thereby not permitting any differential rotation. So there can be no level within the divided axle association that Da Vinci’s sketch confirmed so clearly, and was adopted by Prof. Galluzzi in his mannequin (determine 5). My psychological evaluation and preliminary Meccano mannequin confirmed that the machine wouldn’t steer successfully with out the wheel(s) skidding!
Did Da Vinci overlook this case, deceptive all the next college students and mannequin makers? Or have I missed some extent?
Determine 5 The 3D CAD mannequin displaying the meshing tambour gears and steering mechanism of Prof. Galluzzi’s challenge
The Meccano Mannequin
However the query above, figures1 and 6 present my interpretation of Da Vinci’s machine through which the tambour gears don’t mesh. Determine 6 is an overhead view of the deck with the Da Vinci machine options annotated and as interpreted within the mannequin.
Determine 6 Options of the Da Vinci self-propelling cart as developed in mannequin type
The apparent subsequent concern was reproducing the clockwork mechanism. It may very well be imitated by utilizing two Meccano clockwork motors; nevertheless, I wished to repeat Da Vinci’s intent, initially no less than.
So a seek for appropriate clock springs which may match right into a Boiler Finish was made, with none success, till I consulted a horologist good friend who referred me to Meadows & Passmore’s website which lists a wide variety of clock springs. The primary gap finish spring I ordered (13mm extensive x 0.4mm thick x 50mm diameter) proved to be far too highly effective to comprise inside a Boiler Finish with out distortion. The second (10mm x 0.28mm x 28mm) proved simpler to deal with and I managed to seize the inside finish through its gap, onto a Key Bolt with the tip floor off, fitted right into a Coupling. The outer finish was equally connected to a shortened Bolt passing by the Boiler Finish flange.
With the one wheel pushed by this spring the cart travelled about two toes! This proved the feasibility of the system, however clearly far more improvement was required in lowering friction and optimising the spring properties.
The Boiled Ends had been connected to 95-tooth Gears which drive 25-tooth Pinions to every Spoked Wheel through 19-tooth Pinions and 50-tooth Contrate Gears. The cams for the ‘programmable steering’ are Threaded Bosses. As it’s tough to duplicate the leaf springs of the steering and escapement mechanisms, I improvised utilizing Rigidity and Compression Springs. The third steered wheel is a 1½” Pulley with out Boss. The steering arm rack and pinion adjustment is by plastic elements.
The brake is a Trunnion, the flange of which engages with the 95-tooth gear enamel. That is spring-loaded in engagement to behave as a ratchet when winding the springs. It’s launched by urgent the collar on the rear of the cart; disengagement is maintained by a toggle association.
I used to be at all times sceptical of Da Vinci’s ‘escapement’ (velocity regulator) and the primary technique I adopted to duplicate it was not very efficient. The interrupting motion of the ‘flipper’ wastes energy because the spring unwinds. With the minimal velocity regulation management, it was needed to suit tyres within the type of ‘Meccano’ elastic wrist bands to the driving wheels so as to stop instantaneous wheel spin on launch of the brake. The efficiency was brief lived in time and distance and using compression and rigidity springs critically restricted the ability to the wheels. A a lot decrease charge system is required to attenuate the ability loss; possibly elastic bands can be higher?
Determine 7 Underside view displaying one spring set up and different element
Additional Growth
A centrifugal governor may very well be extra environment friendly, so a small governor design is in improvement which is able to match right into a 1–1/8” Flanged Wheel. The design precludes using friction parts because of its small dimension, so it depends on the centrifugal drive between Collars and the inner cylindrical floor of the wheel flange.
As Meadows & Passmore’s out there spring inventory was restricted, I searched elsewhere and located HS Walsh and Sons, who listed a extra helpful vary of sizes for my software. A few of the issues of coping with and deciding on clock springs are issue in attaching the ends of the spring to the barrel and hub (this will depend on the outlet dimension within the spring ends) and separating the coils so as to make the connections when the spring is coiled! It may be very harmful if the spring constraint is misplaced and it’s allowed to freely uncoil — an aggressive jack-in-a-box! Presumably clock makers have developed methods for dealing with this case.
A HS Walsh and Sons 11mm x 0.3mm x 30mm spring has been earmarked for additional experimentation.
See extra photos of this model.
References
- Hooper, John. “Leonardo’s automobile delivered to life.” The Guardian, 24 April 2004, www.theguardian.com/world/2004/apr/24/italy.arts. Accessed 15 October 2021.
- “Self-Propelling Cart.” Leonardo3 Museum, www.leonardo3.net/en/l3-works/machines/1441-self-propelling-cart.html. Accessed 15 October 2021.