Djbeffects
Airman
- 14
- Jun 6, 2021
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Thanks for your response. Yes I believe British and 1940's but I know little else.Maybe in the meantime you can expand a bit on the type of aircraft these were used on. I can see that it's probably a British unit from the number but the timeframe may be important. I have a little bit of knowledge of late war Mosquitoes and I believe their systems ran on 24V DC.
Great yes I hadn't thought of that I will try latter and see how I get on.Just use the ohmmeter. If it indicates a quite low resistance it means that there is a short circuit. If it is 0 it means no current flow. You may use a multimetr with the function Buzzer that can help with that.
Great interesting. The more I hear about it these were most likely 24V DV and the coils have degraded apparently a common problem even at the time let alone 70yrs latter! Many thanksVery different in shape - but this is the British small bombs container (1943) with three bomb release units. The 'jaws' hold the drop bar.
From what I understand (which is usually little) they're operated by 24 volts DC.
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Useful information thank you I will look into this.You may want to see if you can get a full copy of Air Publication AP 1664 from Kew. https://www.nationalarchives.gov.uk/
I have a partial copy that covers only single hook type. Maybe a full copy will have the one you are wrestling with. Good luck.
Very interesting thanks for your reply and document.Many of the RAF units were 12v DC and as far as I know there were no RAF AC Release units in WW2. Certainly the Lincoln was still all DC on that subject.
The attached file predates what you are looking at but may be of interest. Sorry about the watermark but I do not want unscrupulous web sites selling copies of a document I provide FOC.
My copy of AP 1664 also only covers a small number of units and not that one
The RAF used some weird voltages in AC so, if AC you will need to know what voltage and frequency. There are plenty of online sites covering making AC power sources that run from mains or battery.
Thank you so much for this detailed reply.They are not WW2. The No 1 Electro Magnetic Release Unit (EMRU) was used in the Avro Triple Bomb Carrier of the Canberra aircraft and in the Valiant 5 Store and and Victor and Vulcan 7 Store. bomb carriers. A single unit was used also in the Victor bomber tail drag parachute to operate the parachute doors. The unit IS 24 volt DC supply actuated but in service use the supply from the aircraft was 'pulsed' to avoid 'stiction' nevertheless it should actuate with a straight 24 volts DC
During my RAF life I used to service these. On the left side of the case (face up) are two copper contacts. Try applying 24 VDC to ONE contact at a time with the other probe on the case (earth). You have, probably, found the manual release plunger on the top corner. Depressing this should open the jaws. When open, use thumb and forefinger to close and lock them then manually release. Do this several times to loosen up the internal gunge. Have you opened the case yet? If you want to, ask and I will give you some tips.
Thank you so much for this detailed reply.
Yes I can get the manual push button to operate the jaws and they reset as you describe. I will try touching the positive on the copper atrips as you have mentioned.
I'd be interested in any pointers you can give for servicing, what to look for etc.
Thank you so much.
Regards.
Dominic
Thanks again all very useful information!One of the two contacts on the side is the RELEASE and the other is COCKING. The latter is open circuit when the jaws are open and with the jaws closed and locked completes a circuit to earth. When installed a test box connected to the carrier would show green lights for those EMRUs that were correctly closed and locked. The test box injected only about 4.5 VDC. If you inject an uncontrolled 24VDC to the 'Cocking contact' with the jaws closed it will be a dead short.
Thanks again all very useful information!
Do you know what loads (weight) these were tested to carry?
Many thanks
Dominic
Yes, they were rated for a 1000 pound HE Bomb which was for Canberra and the three V-Bombers the standard conventional bomb, 6 x 1000 for Canberra, 21 x 1000 for Valiant, 35 x 1000 for Victor and (I think) 21 x 1000 for Vulcan. As a young Armament Fitter I worked Canberra/Victor/Valiant. Because the Victor tail brake parachute installation used the No 3 EMRU (big brother to the No 1) to hold the chute shackle and the No 1 EMRU to operate the doorsthe task of fitting the brake chute fell onto the 'plumbers' (Armourers)