The Lovely Patent Plate

TD owner, Laurent Castel from the South of France has been researching the Patent numbers shown on the Patent number plate on his car. Here’s what he has found…

“The shiny patent plate of my TD shows mysterious numbers. We all guess that those numbers refer to some smart processes that make our cars so pleasant.

A few internet queries can provide answers to these mysterious numbers.

One can browse to read the complete specification of the patents including original drawings.

As a cultural interest, this article presents a brief synopsis of these patents. I’m not a legal expert so my reading only focuses on technical aspects.

There are 12 patent references and one registered design on my 53 TD plate. How different is yours? What about other Ts?

Only one (532566) couldn’t be documented from my internet efforts, for unknown reason. The registered design is only available at British National Archive according to their website.

Too far from my home!

N° 495125
Date : November 8, 1938
Authors : Reginald William Ryder

The patent describes a staggered pattern of the cooling tubes of the radiator. The tube section is oval and each tube row is somehow overlaying the neighbouring ones.

Furthermore, the horizontal cooling plates that maintain the tubes have bumps between the tube holes. Morris claims that this improves the cooling feature for low speed air flow and even for oblique air flows. The bumps slightly deviate the air flows and probably increase the cooling feature of the plate. All cooling radiators today include louvres on the plates between tube holes for this reason.

However, I doubt of this improvement for oblique air flows!

What is actually oblique air flows in our cars? Cornering or very low speed with lateral strong winds? Anyway, these conditions never last more than a few seconds. Too short for overheating the entire engine.

The text states that the author is aware of a similar US patent dated 1934. The US patent claims a special arrangement of the radiator elements to cope with the whistling effect of radiators at high speed. Therefore, the goal of this similar process is different.

Staggered pattern and oval section tubing is still in use today. My radiator was not original so I have no clue if this patent was implemented in TDs.

N° 437562
Date : October 31, 1935
Authors : George Alfred Priestley

What a surprise to discover that the sliding mechanism for adjusting seat position in modern cars still relies on this Morris 70 year old patent! The patent is partly implemented in TDs. Sliding devices are directly from the patent but locking mechanism and seat removal are different.

N° 527468
Date : October 9, 1940
Authors : Alexander Arnold Issigonis

Rubber pad for suspension springs.

The invention claims a better spread of the thrust on the suspension arms.
Obviously, there is no rubber pad on either side of the suspension spring of my TD.

N° 502031
Date : March 9, 1939
Authors : Alexander Arnold Issigonis

This patent is not a user improvement. It is just an industrial simplification. The purpose is to facilitate the manufacturing of the independent front wheel mounting. Only one steel part with two perpendicular holes for the king pin and the steering lever. It’s interesting how Morris was concerned about factory problems, but these would affect manufacturing times and eventually final production costs.

It seems that cost is today’s main concern and, sadly, sometimes the only one for any industry but, back in the 30s, the performances and the quality were probably the leading aspect for any conception.

This invention is still implemented in TDs.

N° 502029 and 502030
Date : March 9, 1939
Authors : Alexander Arnold Issigonis

Here is described the threaded swivels in the front wheel steering design. N°502030 patent also claims to be only a manufacturing improvement. Axial bearings or thrust bearings are no longer necessary. A good article in TTT N° 40 explains, from Issigonis notes, that this gives a lighter steering than conventional non ball bearings and that lubrication is more effective and more protected.

N°502029 describes a solution for applying the preceding one but in the case of the steering axis of the hub shall lie in the same plan that the upper and lower pivotal axes of the suspension arms. Although 502030 is implemented in TDs, 502029 is not.

N° 502028
Date : March 9, 1939
Authors : Hubert Noel Charles

The patent describes a combined suspension system for front wheels with laminated springs and a sort of half anti-roll bar. This enables the use of relatively soft springs and even minimises the steering interference when brakes are applied. When braking, the sagging effect of the spring is counteracted by the upper rod which is then compressed. Furthermore, it is also mentioned that linking nearside and offside previous systems acts as an anti-roll bar.

N° 511064
Date : August 14, 1939
Authors : William Robert Boyle

Chain tensioner: damping function and/or tensioning.

One means of linking the camshaft and the crankshaft of engines is to use a chain; but the chain wears and needs a chain tensioner. The invention is an automatic chain tensioner.

The invention relies on the hydraulic power which is available in engines based on the pressurized lubrication circuit. This is really a good idea since the oil circuit is running very close to the chain for camshaft or crankshaft bearings. The invention also describes an additional spring inside the piston for static pressure. A combination of a piston special design and the spring action can act as a tensioner and a damper.
This invention is implemented in the XPAG engine of our TDs.

N° : 539083
Date : August 27, 1941
Authors : Alexander Arnold Issigonis

This invention allows the oil and air to flow from one end to the other in a rack and panel steering mechanism. The cross section of the moving rack must be different from the housing where it is sliding in. Morris describes an example in which the housing cross section is round and the sliding rack cross section is square shaped. The angles of this square shape are rounded to fit the inner section of the housing. Therefore there are 4 passages for air and oil from one end to the other. This patent is implemented in TD steering mechanism.

All these patents are pre-war. This is strange that 12 years after, no additional patent is displayed on the plate. Did Morris declare some more and did not change the plate? Alternatively, we could realize by this lack of patent how the T series needed a global renewal. However, as an obsolete car, compared to popular French cars in 1953, the TD was still advanced technology (rack and pinion, twin leading shoe front brakes, 12 V battery, spring front shock absorber, adjustable steering wheel?). Obsolete in 53, still a pleasure today!”

Ed’s note: Laurent asked me to check his (very good) English. I have made one or two alterations and in doing so I hope that I have not spoilt the text.