[David Dunlop]

A little, but productive, task today.

I cleaned up the heads on the two Studs, Cowl Fasteners, Shakeproof while they were still attached to the front panel of the vibrator supply. I have been very curious about these parts for some time. I will also be asking Shakeproof about these items in the New Year to see if more answers can be found and some ideas confirmed.

In general, these Wing Head Cowl Fasteners, like their larger ‘AirLoc’ cousins, which are also used on the 52-Set, come in various stud lengths. These lengths are typically number coded and I do not as yet fully understand how that coding is based. In general, I believe the larger the number, the longer the stud length and the stud length is determined by the distance, or space the stud needs to pass through in order to have the small pin at the end of it engage and lock into its spring steel receptacle.

The 1945 Issue 1 of the Illustrated Parts Manual that Canadian Marconi created is assembled in sections and that makes it very easy to find things once you become familiar with the layout. The down side to this, however, is this manual results in a lot of repetition. Any parts used in the Receiver, will also show up in the Sender Section and the Supply Unit Section and anywhere else they were used. The 1949 Issue 2 of this manual removed all that duplication so it is a smaller size, but in some circumstances more vague to work with when trying to sort parts out. These Shakeproof Cowl Fasteners are a good example.

A pair of these Shakeproof Cowl Fasteners is used on the Receiver Vibrator Supply, and another pair on the Blower Access Door on the Sender. The two sets are different sizes.

When I was working on the Sender, I found the upper cowl Fastener was a Shakeproof 18. It locked, but the pin in it was bent in a ‘V’ towards the end of the stud and it looked like only the very tips of the pin were engaging the receptacle. The lower Cowl Fastener was not a Shakeproof product at all. It was a Dot 230, noticeably smaller and flimsier in design than the Shakeproof one. One half of its pin was broken away, but it seemed to be engaging its receptacle just fine.

When I was reassembling the Sender, I had to install new pins into the two cowl fasteners in the Blower Access Door. With them installed, I discovered the upper Shakeproof fastener did not reach its receptacle at all, the pin spun freely in front of it. Initially, the lower Dot 230 cowl fastener seemed to be working, but it was only catching one half of the pin between the receptacle and its mounting plate. So again, not the correct size on a number of levels. I then started a closer look at the 1945 Parts List. It showed that Shakeproof No. 18 Cowl Fasteners were used on the Sender Blower Access Door and Shakeproof No. 21 on the Receiver Vibrator Supply in the Supply Unit. That struck me as odd since the one No. 18 on my Sender was clearly too short. Hence my heightened curiosity about the two cowl fasteners on my Supply Unit.

It is hard to see because these items are so small, but both fasteners on the Supply Unit are Shakeproof No. 18’s, and both work perfectly. In the first photo to the left of the wing head, a classic, typewriter style lower case ‘i’ (without its dot) is stamped on the stud head. To the right is stamped an ‘8’. In the second photo, ‘SHAKEPROOF IND’ is stamped across one side of the wing head.

So my conclusion in all this is that when the 1945 Illustrated Parts List was assembled, the data for the two Studs, Cowl Fasteners, Shakeproof on the Sender and Supply Unit got reversed and the proof reading did not catch the error. Hopefully, Shakeproof may still be able to provide some information on this product regarding the size codes, and perhaps more.

David