In the USA there are 2 or maybe even 3 in Minnesota at Drive-A-Tank, and also one more runner in New Zealand at Christchurch, used to be a tank driving adventure, ex-Vietnam vet.

Malcolm, have you counted the links in the track? I know there is an acceptable wear guide which allows for the removal of a link, maybe 2-3, can't remember the exact number. I remember a fellow in Australia who had removed too many links and the track was tight as a piano wire, eventually he ended up tearing off the idler or the final drive.

When we got ours it was new track but loose and it wanted to jump the sprockets...no fun tightening Centurion track without the proper ratchet tool!

Christchurch
Attachment 110476

John,

Can't quite make out the ARN in your image - is it 169039?

Regards

Mike

Mike this is the info on the Christchurch tank that I have:

The tank is now called Maximus I believe but in Vietnam it was "Cromwell" C/S 2 was ARN 169039's last name prior to leaving SVN. 2 troop, C Sqn 1 Armd Reg.Tour date Dec 1970- Sept 1971.

Attachment 110479

Attachment 110480

Thanks John, interesting to see where 169039 ended up.

I used that period image by Army PR photographer Bill Cuneen on page 301 of 'Mud and Dust'. The tank was named by the crew commander, 2Lt Ian Farrant, who told me during the interview I recorded with him that '...on taking command of 2 Troop, I discovered all four crew members of my tank were born in the UK and therefore thought it appropriate to give it an English name. As an avid military history student I was very much taken by Cromwell as a military leader and thus named my tank after him.'

More from that interview is presented on pages 146-147 of Mud & Dust. Nice bloke: very reasoned in his responses to my interview questions.

Regards

Mike

John,
The tracks came new with 108 links. The users manual says when you use up all the threads available on the tensioner trying to set the correct sag, you need to remove a link. When you are down to 102 links, get REME involved.
That's 6 links you can remove, which surprised me since that's about 2.5 feet of track!
We've got 102 links on one track and 103 links on the other, so we're still good, barely.

The problem is when I loosen the tensioner nut off to slacken the right hand track, which is way too tight, the tensioner doesn't back off, even when I drive the tank in reverse. So it's jammed. Looks like I'll need to get medieval.

Malcolm

Malcolm

could you push the track up against some other heavy object? (another tank comes to mind) and just give it a push and see if the idler will budge backwards?



John

John,

Depending on which type of idler is fitted (there were three designs), that method may risk breaking the idler.

Mike

We got medieval today. Heat, pounding and jacking were involved, but the key step was tightening the tensioning nut back up with a 3 ft pipe wrench and a 6 ft pipe extension. This actually cracked the tensioning screw loose from its spherical seat bushing and with some more heat and jacking the track off the top of a road wheel with a 20 ton jack, we got the tensioner loose enough in the seat that a quick application of right hand neutral steer would pull the tensioning screw back.

The pic below may make my description easier to understand.

Malcolm

Attachment 110555

Centurion update.
 

We're restoring a Canadian Centurion at the Oshawa Regiment museum in Ontario, Canada.
I wanted to give an update because it's actually starting to feel like we're getting somewhere!

She's running and driving with the rebuilt Meteor we got from the States, although only inside so far due to my reluctance to get clay mud all over the undercarriage when we are in the process of cleaning and painting it.

The engine starts really well. The key is not to use that stupid choke plate (aka strangler). God knows why that is installed. All that happens is the full intake manifold vacuum acting on the carbs sucks huge amounts of fuel through the main jets and because it's an updraft carb, none of this fuel gets up into the intake manifolds because the choke restricts the air flow so much, and it all dumps down into the plenum and pours out of the automatic plenum drain tubes. Rolls Royce designers obviously weren't idiots so there must have been some logic behind the choke design but I don't know what it was.

Anyway, I have a electric priming pump installed to fill the carbs to save the hassle of using the rather inaccessible priming levers on the installed fuel pumps. After that, 3 or 4 pumps on the gas pedal (which does shoot gas up into the intake manifolds) and she fires right up.

The clutch rebuild showed the massive plain plates and friction plates were all still in spec, and only a couple of new bearings and seals were required. It works well and is much lighter in operation than I expected.

Steering, including neutral steering, also works very well, which is a relief as all I did with the transmission was remove the top covers to do a visual check of gears and shifter mechanism. All looked good and fishing around the bottom with a magnet picked up no worrying pieces, and oil was clean. The final test will be driving it around the arena to confirm that all gears are there and shifting is manageable.
One thing I noticed is that there is a shift lock-out mechanism (to prevent the selector mechanism from trying to select two gears at the same time) in the gear selector box up in the driver's compartment, and also in the transmission. So it is very important to synchronize the two lockout mechanisms so that the driver can easily select each gear. I don't think the manual mentioned this requirement.

Right now we are in external bodywork repair and painting mode. Some track guards were beyond repair so new ones were fabricated. All the side bins were really rough too so repair (cutting, patching, grinding, and painting) is in progress.

I should say at this point that, like most museums, money's a bit tight, so management encourages the use of free internal labour to fix stuff, rather that farming it out to a local fab shop. And when I say "encourages", I mean "insists". So we don't always achieve perfection, even though we aim for it. :)

The photo below shows our progress so far.

Even though this tank is nominally Mark 5/2, it came with the full gyro stabilizing power elevation and traverse (which I believe was a later Mark?). It looks quite intact so my personal dream is to get this working and have the only tank at the museum with functioning gun stabilizing. Time will tell.
Malcolm

Attachment 114099

Malcolm, great progress.

dont forget I have some lights for you here, maybe i should post them to you

Nice job, Malcolm, looking much better than when I saw it a couple of years ago.

I think you will find that stab was a feature for all the Cent marks.

Regards

Mike

Robin, to tell you the truth, I'd forgotten you had lights! We've just started working on the lights. Can you mail them and I'll refund the postage?

Mike, I got confused. What I meant to say is we seem to have a later style, more sophisticated stab control, not the system described in the Mk 3 tech manual. Does that make sense?

Malcolm

Malcolm, just to update your post #30, There are two Centurions in the south Island of New Zealand. The one I previously mentioned owned by the gold miner on the west coast, and the one John mentioned in ChristChurch (east coast) Both at similar latitudes. The Christchurch one was for sale on Trademe at one stage. I thought it was cheap, so it may have moved. No idea.

Another update: after getting the bulk of the external painting and metal work repair done, we took the tank for a drive around the arena on a very hot and dusty day. (There are separate threads showing this, I think.)
Two problems showed up: the old oil seals in the transmission and the final drives leaked, and the engine ran hot. Not dangerously hot, but at the upper range of comfort.
I confess the oil leaks from the lip seals on the transmission input shaft, the output shafts (4 seals in total), and the final drive input shafts weren't all that surprising since the tank had been gate-guarded in the late 70's, so the seals were at least 40 years old. I took a flyer because getting the transmission back out isn't a lot of work, and I knew finding replacement seals would be tough.

The overheating problem is most likely because the fins in the one rad are still clogged with an oil/dust mix. We spent hours with varsol and pressure washing trying to clean the fins and hoped for the best, but it it seems we need to do more. These are very thick 8-row rads so crud getting deep into the core is very hard to get out. I'm thinking steam cleaning now.

When's it's running again, I'll take infrared readings of the inlet and outlet temperatures of the two rads to confirm this is the problem.

Regarding the seals, we needed to find seven new seals. I found three seals of the correct size, but the other four were a problem. If the inside diameter fitted the shaft, the outside diameter would be too small. So I ended up getting the seals that fitted on the shaft and buying some mechanical tubing and machining spacer rings to make the seals fit in the housings. I'll post some pics and the seal part numbers for the tiny number of people who care. :)

Malcolm

Malcolm,

I have to ask, where is your tolerance for having new stock of those seals made again at this point? I do find we are living in an age of new production of many items at very reasonable prices these days.

How is your lighting making out?

Robin,
PM sent.
Malcolm

I installed a nice 12 volt oil priming pump today and got 15 psi at the pressure regulating valve where the oil enters the engine. That should be enough to prime the crank bearings and fill the passages up to the cams and valves before cranking.

Headlights are installed and working and the front and rear sidelights are in progress.

The gearbox and final drives are reassembled with the new seals. We've got to clean up and repaint the gearbox compartment and the gearbox before installation.

The two ammo ready-racks have been overhauled and are ready for installation. These hold two shells each, are located beside the loaders seat, and run on rails over a limited part of the turret ring, presumably for the convenience of the loader when he is scrambling for fresh loads, especially under the floor plates.

Much to my relief, we managed to get a voltage regulator for the main engine generator from Tim Vibert in Australia for a good price. He has a lot of parts for Centurions. I needed this to charge the batteries because ours went missing and we don't plan on installing the auxiliary engine/generator for a while.

Malcolm

The Cent got driven around the arena many times today to train some people to drive her. Good news - the new gearbox and final drive oil seals didn't leak. Bad news - one of the rads is quite badly plugged so she's running a bit hot. We have spare rads but they need repaired. It would be boring if she ran perfectly, I guess.

A personal comment on driving these tanks: the increasing turn radius in higher gears is a given for this design but isn't impressive. Even second gear requires quite a large radius. So these tanks were not that maneuverable in my opinion, and hard work for the driver who's busy shifting to deal with varying terrain and corner radii. For tight maneuvering, first gear or neutral steering is required.

I haven't heard this criticism applied to Centurions so maybe I'm too harsh here? But it must have been so much easier for the later Chieftain drivers who had the same gear ratio to turn diameter limitations, but a transmission that was so much easier to select up and down.

Malcolm

Update: regarding the running a bit hot on a hot day, we repaired a spare rad that had clean fins and tubes but had a bad tube leak due to freezing (I think) to replace the one that I thought was plugged with oil and dirt deep in the core. But on further inspection of the supposedly plugged one, I’m not sure that’s the case. So what else would cause a Meteor to overheat on hot days?
When we bench tested the engine, the thermostat opened around 175 deg F so I don’t think that is the problem.
Running lean? I’ve got a wide band O2 sensor so I can check the air fuel mixture under load on both banks since ihere is a welded boss for the O2 sensor on both exhaust pipes. Damn, I hope it’s not a carb problem since they are a bitch to get access too.
Maybe a restrictive strainer mesh in the long range fuel tank we are using as our supply? Or low fuel pressure at high load?
Due to COVID, we haven’t run the tank for any length of time for more than a year, but with a potential Tank Day coming up in August, I’d like to get this resolved.
Malcolm

On another issue, when I select non-STAB mode, which provides power traverse, and only manual elevation (as it’s supposed to), the turret correctly rotates at a speed and direction depending on how the gunner’s or commander’s controller is rotated, as it should.
But when I select STAB mode, which is supposed to take signals from the traverse and elevation gyros to provide full stabilization for the gun elevation and the turret traverse, only stabilization for the gun elevation works (which is very cool, watching the gun stay level as the tank drives over berms), but the traverse stabilization doesn’t work at all, either from the stabilizing signal or the controller signal.
I know it’s a 70 year old tank and I can’t expect perfection, but it bugs me!
Malcolm