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ArtistsRifles

New project - Mk 1 Knocker 6x6

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Seems to be the season or dodgy internet connections for Militant owners - we had the broadband router go down Monday and have only just got back up and running.

During this time the BV for the Militant has arrived, the cable is due any day now. This is the device - latest gen version:

 

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It was advertised as an RAK-15 unit but looking through the manual that came with it (new in box) it turns out to be the slightly larger capacity Model 471012. The paper thing its sitting in is a template for the carrier - I made it in paper first to verify the dimensions were OK. Everything seems OK apart from the depth of the slots for the mounting studs. The unit is sitting at the very bottom of the cut out - but I am thinking of adding a layer of rubber to the base cut down on vibration noise - there is enough of that in a Militants cab as it is so that will lift the studs up the mounting slots. The cable coming is the ones for this type with the round connector one end and what looks like two male plugs going by the sellers photos. That will make installation a lot easier. Just got to provide a supply with a 20A fuse in it. Definitely for use with the engine running only. Manual reckons it takes 20 minutes to boil 1.05 gallons - US gallons I guess - of water for hot drinks and then it will maintain that heat for some 6 hours.

 

The stud on the side is for an earthing strap and I need to fabricate a strap that runs horizontally across the front - standard tongue and buckle - that is fastened at each end to the side cheeks.

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Neil - might also be an idea, if there's enough length on the studs, to put a penny washer and rubber washer either side of the mounting bracket to cut the vibrations a bit more?

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Neil - might also be an idea, if there's enough length on the studs, to put a penny washer and rubber washer either side of the mounting bracket to cut the vibrations a bit more?

 

Nice idea Sean. I think the studs are about 20mm long so it might be possible. Once I make the cradle up I'll be able to measure up. But its certainly a good idea :-)

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Christmas came early today - I had couriers lining up to deliver bits and pieces this morning. Quite a novel experience. :-)

 

First to arrive were the replacement winder mechanisms for the door glass. Probably means the next letter to come will be another VAT demand from HMRC :-) Anyways - hopefully these are now the correct style back plates to fit the Militants doors:

 

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Next in was Robs AEC calendar- the entry for April looking awfully familiar :)

 

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And then lastly the power cable for the RAK-15 boiling vessel turned up. As you can see in the photo - the correct 3 pin plug is fitted at one and whilst the other end has two bare end to I can fit whatever connectors I need.

 

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Father Christmas just ticked another item off the "to get" list this morning - he dropped off a Draper 20 ton jack care of the Daughter Mk1. :-D :-D

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And last and perhaps not least I also managed to acquire on of the seemingly uber-rare 1 gallon oil cans for the rear locker

 

I'd have to check, but I'm sure I have a quantity of those!

 

I presume we are talking about the little can that should live in this rack on my Tanker, if you do have a spare one Sean could you put my name on it, please. Many beer tokens would be available.

 

Just had a look at the workshop. I have cans in several sizes, including the square oil can and the more rectangular one. I had mentioned them before, in the 'What's Sean got now?' topic.

 

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Both are around 11 3/8" (288 mm) high plus handle and lid. The squarer ones are about 5" x 6" square and the narrower ones are 4 3/8" x 6 1/2" square.

 

None are mint, but all are pretty good and all have 1950s dates. Most of the square ones are embossed WD & broad arrow.

 

Also have some small one quart cans as you can see from the last photo.

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Looks like some good news tonight! Been hunting for a spare distribution valve for the air brakes since I got the Militant and looks like that has paid off. Heard via e-mail from a firm called Erentek (www.erentek.co.uk) tonight - they say they can supply the valve for £90 + carriage and VAT. So I've asked them to order me one - once it arrives it will- I hope - be a straight forwards 1 off, 1 on operation and then the brakes will be 100%

Once that is done then the old girl will be usable and can be taken for runs, panel work permitting :-) :)

 

EDIT: final price inc. VAT and carriage is £126.00

Edited by ArtistsRifles
Final price added

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Good news - the new valve for the air brakes arrived today!!

 

If the weather is OK then hopefully I can have a go at fitting it next weekend.

I say hopefully because looking at it today - there are more sealing plugs than I have hose connections!! But the valve does look to be the same if you compare the photos below. So I am hoping the existing one has some blanking units in it.

 

This is the new valve:

 

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And this is the old one on the vehicle now:

 

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Finger crossed all will be well. :-)

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New valve was fitted yesterday. Went reasonably easily (thank god for very large adjustable spanners). The fears over corroded unions and pipes proved groundless. The hardest part was getting the old blanking plugs out as they were allen key types rather than hex heads. Thats the good news.

Less good is that on starting up and building air pressure there was still a leak from the same place :( When the unions were transferred across it was found that the apparent source of the leak wasn't actually a pressure relief valve but an exhaust valve. So the air leak must be further up the system. Next suspect after talking on the AEC forum is a leak from the foot pedal valve. When it warms up a bit more this will be investigated.

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These things are sent to try us, they say. Brakes though, have to be right, you can't be bodging them up and hoping for the best.

 

You'll probably find most of the issues will have been caused by her sitting around doing nothing for a long time. Once you get it sorted and are running her up now and again on a regular basis she will be better

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These things are sent to try us, they say. Brakes though, have to be right, you can't be bodging them up and hoping for the best.

<snipped>

 

 

Exactly so mate!! I will not be using the old girl until this issue is resolved. I'm not an expert on air brakes at all so question is - if I disconnect the outlet union from the foot pedal valve and run the old girl up to pressurize the system - would I be right in thinking if the foot valve is good then there should nothing coming out from that union??

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Correct.

 

Cheers :) So then - next step is to:

(a) Identify the valve in question,

(b) Locate it on the vehicle and

© Persuade the outlet union to come off!

 

Hopefully that will be the source of the problem - if its not then at least that can be crossed off the list.

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Neil,

 

But.. if it's the inlet valve that's leaking, which I'll guess is the most likely (where crap enters the foot valve), then the air will leak out of the foot valve body. I don't think it can leak to the outlet (with any pressure) when the pedal is up because the exhaust valve is open - venting the brake line to atmosphere.

 

Prepared to be corrected by Militant buffs. Shields up.

 

Phil

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Neil,

 

But.. if it's the inlet valve that's leaking, which I'll guess is the most likely (where crap enters the foot valve), then the air will leak out of the foot valve body. I don't think it can leak to the outlet (with any pressure) when the pedal is up because the exhaust valve is open - venting the brake line to atmosphere.

 

Prepared to be corrected by Militant buffs. Shields up.

 

Phil

 

In all honesty Phil - I have no idea - my knowledge of air brakes is minimal at best so I am on a steep learning curve here. I used to drive them, not maintain them. :)

 

All I know at the moment is there is air constantly escaping from the exhaust valve by the rearmost axle - enough to drain the air tanks within a few minutes of stopping the engine. That rear valve has been replaced with a brand new assembly thus (in theory) eliminating that as the source of the problem.

 

As I understand the system thus far - and I'm always open to correction here - being a 1959 vehicle it is an simple "air on" type - that is, the air pressure applies the brakes as opposed to the more modern system of "air off" where the air pressure holds the brakes off.

For operation - the compressor charges the air tanks, these feed the compressed air to the foot brake valve under the cab floor so with the pedal up the system past this should be "dead". Pressing the pedal to apply the brakes opens this valve allowing air into the system and applying the brakes, lifting off the pedal closes the flow of air allowing what is in the system to vent and release the brakes. This is how I think the system works so again - if wrong - I am always open to correction!

 

I am assuming therefore that the fact that air is constantly escaping from the exhaust valve suggests that there is a leak in the system at the point where the air is allowed to enter the system - which is that foot brake valve. I cannot think of anywhere else it might be. I am guessing either something is sticking or a diaphragm has gone after being left standing for 3 years.

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Could that relay valve be part of the trailer braking system? As opposed to the vehicle system, just thinking as the Martian has two relay valves, one for the truck and one for a trailer. Is the trailer hand valve ok.

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Could that relay valve be part of the trailer braking system? As opposed to the vehicle system, just thinking as the Martian has two relay valves, one for the truck and one for a trailer. Is the trailer hand valve ok.

 

The valve replaced was purely for the rear brakes - one feed entered it and two came out - one to each of the rear axles.

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On modern trucks air pressure holds the parking brake off, the service brakes are increasingly fly by wire signals to operating valves. Older models are full air actuation from the foot operated valve to a proportioning valve to differentiate between front and rear axles with load sensing. A piece of dowl wood is handy for hearing internal leaks without dismantling pipework. A none return valve between compressor and main air tank is oftain a scorce of trouble. I would start at the foot valve that is a problematic piece.

Edited by john1950
edit

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The valve replaced was purely for the rear brakes - one feed entered it and two came out - one to each of the rear axles.

 

Feeds must go to the left and right rear actuators. There aren't separate actuators for each axle. One each side pushes a tube to work one axle and pulls a rod to work the other. Not an ideal set up as if they aren't set up perfectly (ideally with a rolling brake tester) one axle will brake really well and the other will do nothing. Even worse you're also trying to have equal braking across each axle.

 

I've never had any worry mine won't stop, even as a 16.5 ton camper, but it was always a trial each year to get through a test as an HGV. As a heavy class 4 using a Tapley meter it is easier, although trying to stop with the ratchet handbrake (secondary braking system!) in a small workshop yard tests everyones nerve!

 

Once your leak is solved you can always check the brakes with a voluntary brake test at a testing station.

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I'm not quite sure I'm the Militant expert who will answer all the queries, but for it's worth, here goes.

 

I have 2 parts books for Militants, a '57 example for the Timber Tractor (That's the short wheel base HAA Tractor) and a '54 one, which I got from Neil, for the tanker. Neither show any form of valve of with an exhaust port anywhere near the rear axles.

 

The 2 rear brake actuators are fed from a single pipe from the foot pedal valve, with a "T" piece part way down the right hand side of the chassis.

 

There are a couple of non return valves that prevent air transferring from the trailer brake lever valve into the trucks brakes, but otherwise it is a sealed system.

 

I haven't physically checked the tanker, but the timber tractor brakes, exhaust back through the foot pedal when it is released.

 

As was pointed out earlier, Militant brakes are single acting chambers, until the pedal is depressed the system will be dead. The only air pressure will be in the trailer red line, which is constant pressure to feed trailer air tanks.

 

It would be my guess that as Neils motor is much newer than my two, this additional valve is a modification to the original design, or it is the trailer pressure leaking back through a non return valve.

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If you cant track it down easily, a spray bottle with fairy liquid for some bubbles?

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This is the ISPL diagram for the "Power Brakes" - I tried to fill in the various air paths to make it easier to follow. Red is the path from the foot brake valve to the rear distribution valve where the leak of air can be heard and felt from the exhaust port. As you can see - it is a very basic system. Blue is the path from the air tanks to the foot brake valve. Yellow is the front service brake connector Had a couple of pointers from the AEC community tonight: * "Check the plunger under foot valve pedal it's got a rubber boot covering the plunger , this gets dry and sticks" * "If it's leaking from the breather and was doing so with the previous valve then I would suggest it is being fed from the foot brake valve which is leaking internally. Memory is weak after 40+ years, but as a relay valve it should have a feed (usually the central union) and trigger line from foot brake the third union is delivery. Build up air pressure and check each union there should only be air to the centre union until brake is applied" So next chance I get to get over to the vehicle I will have a look at these as well airbrake%20diagram_zpsttrgxobd.jpg

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I also have a few Militant manuals, and each one has a different diagram in for the air brake system!

 

Is this the component that you are looking at?

 

relayvalve.jpg

 

If it is, the drivers handbook has a procedure to check it's operating correctly - it's main use seems to be connected with the operation of the trailer brake lines.

 

Nick

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