Help identifying Douglas A-20 part P/N 4055762 (1 Viewer)

[EnneBi]

Hello everyone,

I'm trying to identify a mechanical component recovered from a Douglas A-20 Havoc/Boston wreck site.

After dismantling the assembly, a clear marking appeared on the small circular component:

P/N 4055762

The unit consists of a small drum-like element, a curved band around it, a lever system and an adjustable threaded rod. From its construction, it appears to work as some kind of friction device / band brake / torque-limiting mechanism, used to resist or control rotational movement.

At first we considered the possibility that it belonged to the nose wheel snubber system, but after checking the original A-20 maintenance manual this now seems unlikely. The actual nose-wheel snubber shown in the manual is a completely different hydraulic assembly.

The number format appears consistent with Douglas part numbering, but so far I have not been able to find 4055762 in the documentation available to me.

I would be very grateful if anyone with access to the Douglas A-20G/J Parts Catalog AN 01-40AL-4, or other original Douglas parts documentation, could check this number or recognize the assembly from the photographs.

I can provide several detailed photos of the dismantled component, including close-ups of the marking and internal construction.

Many thanks in advance for any help.

 

[cvairwerks]

Not in the IPB's for G, J, H or K models.

Photos would be helpful.

 

[Jadera]

Yeah some photos would be great.

 

[EnneBi]

here are the photos!

 

[EnneBi]

Not in the IPB's for G, J, H or K models.

Photos would be helpful.

Thanks for checking.
I've already uploaded several photos of the complete assembly and the dismantled parts, including a close-up of the 4055762 marking.

The part was recovered from the same A-20 wreck site. From the construction it looks like some kind of friction / band-brake mechanism, but we have not been able to identify its exact function yet.

If it is not listed in the G/J/H/K IPBs, I'm wondering whether it could belong to an earlier A-20/DB-7/Boston version, or perhaps be a sub-component not separately listed in those catalogs.

Any thoughts would be greatly appreciated.

Best regards

 

[smutny]

That's a 1, not a 7. 4055162

In the Illustrated Parts Breakdown for Douglas A-20H & A-20K, AN 01-40AP-4

That assembly you have is depicted in Figure 67 on page 109. It's the Rudder & Elevator Trim Tab Mechanism.

4055162 is a Drum Assembly for the elevator trim tab. (Although the IPC calls out for 4 of these in the aircraft and this one is on the Rudder Mechanism)
The larger bracket, 511429, is the Support Assembly - Rudder Trim Tab Mechanism
The shaft is 21144087, Shaft Assembly - Rudder Trim Tab Mechanism

The arm attached to it, is not depicted in that figure.

So the cable wraps around the drum, when it turns the shaft moves in or out and then the arm makes something happen. Curious as to what you eventually figure out how this whole assembly worked. Please keep us updated.

 

[SaparotRob]

I love this place!

 

[cvairwerks]

With the drum being 162, it makes a difference and shows in multiple IPC's for the A-20.