DOUG'S 'HEAVY METAL' GALLERY

 

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"Heavy Metal".

Driving an M113A1 APC.

   (Ver 2)

 



  Just like the previous Centurion article, this account deals with the sounds and impressions of a civilian (me) in an AFV.

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My first experience with a tracked AFV was driving my own Stuart Light Tank and although there is a world of difference between an APC and a Stuart, the basic handling is the same. Take a close look at the controlled diff of the M113A1 and you are in no doubt as to its lineage back to the Stuart and its predecessors.

First impressions of an M113A1 up close is that you are standing alongside a blank wall. I have come across the odd 6'6" tall person who can look across the top of an M113A1 but for the rest of us, if we want to see on top we have to climb. Which is not quite as straight forward as you may think. There are 5 practical ways plus the spectacular military way:

1) The military way: is to charge the vehicle from front on at a full run, you then spring up the front LHS (where the spare track link lives) and keep running until you are on top of the vehicle. Providing that is, you haven't slipped in the process and shattered your knee cap, entangled your foot in the spare track link or light guard and broken your ankle, slipped and shattered your shin or some other painfull accident. There is of course the large hole where the driver lives to avoid once you have arrived at speed on top.
Commonly seen on the ads on TV. These are actually just set up to look good. OH&S has stopped all actions like these.

2) You can always use this same route but do it slowly and carefully. To do so requires climbing the track (a no-no for safety reasons) or using the tow fitting on the bow plate as your initial footing, however these are very easy to slip off.

3) The next way is to go to the back of the vehicle, insert your foot in the hole in the rear mudguard, grab the handle at the top of the vehicle and as you swing up stand on the Jerry can rack with your other foot. So far so good, but where most people get wobbly is that there is now nothing left to grab and you basically have to stand upright and move forward from there.
If, however, the Jerry Cans are fitted, you will need to have the physique of an Oranguatang.

4) Lastly you can enter via the crew hatch in the LHS of the ramp. Providing it is unlocked, which quite often is not the case as the lock catch is a temptation for those who must fiddle.

5) If track shrouds are fitted, stick your right foot in the foot cut out on the front shroud anchor plate then your left foot on the spare track link and get on that way.

6) If the ramp is down, you can just walk in: which is probably the ultimate way to get on board an AFV.

Now there are several other "approved methods" but these are dependant on whether or not someone is occupying the driver's seat, whether or not they know you are getting on/off the vehicle and whether or not the engine is running.

As regards riding in the troop compartment of a closed down M113A1 or FV 432 I do not recommend it unless you are a real enthusiast. If you are at all prone to claustrophobia then give it a miss as you will be as unhappy as a cat on a hot tin roof. Essentially you will be in a dark noisy box with no idea of what is happening. The bumps, sudden stops and turns will have you lurching and getting thrown around and the passage of time is at a much different rate to normal. The most you can see is the lower portions of the commander and/or driver and the limited amount of light coming past them from their hatch holes. The interior will have a strong smell of oil and diesel which doesn't help one bit and with the vehicle motion combine to induce travel sickness.
If the cargo hatch (large roof hatch) is open, it is quite a different story, you just stand on the foot plates and lean against the rim whilst holding on to whatever piece of bracket or fitting is most convenient and enjoy the ride. Being able to see also means that you have a better idea of the terrain and situational awareness of any bumps, steering correction or stops. The military define it as "a 3rd class ride is better than a 1st class walk any day". Personally, I regard riding in the back of a closed down APC as equivalent to a visit to the dentist.

The Drive and the Ride.

My first drive of an APC actually began in reverse off a semi-trailer. Not a way I would recommend for a beginner. But it does serve to show that they are not hard to drive if you have had previous tracked experience, especially if you do it slowly and carefully and have total trust in your ground guide - which is totally a personal decision........

The vehicle has a Detroit Diesel V form 6 cylinder "blown" (inherent super charger) 2 stroke engine. When in reasonable condition these engines start almost instantly, have good torque characteristics and are a proven and very reliable unit. They are noisy without being deafening and fit the image of an AFV power plant, however, the manual does call for a minimum hearing protection of a headset or helmet and states that ear plugs should also be worn. The transmission is an Allison automatic which only differ from a civilian auto in that they have no "Park" setting, other than that, the gear change is noticably "harder", but okay.
The one thing that these engines really hate is being "blipped" (reved in neutral - the sort of thing every rev-head loves to do to petrol engines - vroom vroom vroom.....) it is a pretty quick way to shear the super charger drive shaft. This is not predictable however and can happen immediately or any amount of time later, particularly under load - the result is a dead engine as they will not run without the blower (super charger) as they are a "forced draught" engine. It is not that big a job to change the blower shaft, but spares are not carried, so it usually means the end of the day's fun. The other thing they dislike is too much idling, it clogs the injectors. Trying to warm up a 2 stroke DD in neutral is a lesson in futility, they don't warm up until under load.
A word about diesel runaway. If an an injector sticks open. The engine will continue to increase RPM until it throws a rod or is switched off immediately (actually, you pull out the engine stop handle - then run like heck). It is quite a scary scenario when it happens to you. Even for Alex, who was a mechanic on these vehicles "I panicked a bit when it happened".

To operate the vehicle you only have to read the detailed instructions so thoughtfully provided by the manufacturer, they take up most of the 3 1/2' high by 2 1/2' wide engine cover panel to the right of the driver - but here it is in summary.
The "laterals" (steering levers) are pulled back and locked in the hand brake function (a button on top of each lever).
Before starting, someone needs to confirm the intercom is switched off and that it is only switched on once the engine is running.
Starting is a matter of turning on the power, selecting neutral and pushing the start button. If the ramp is down it needs to be raised using the hydraulics and locked with the large lever over the driver's right shoulder. Many are those who have embarassed themselves by driving off with the ramp dragging along behind them....... myself included!

The appropriate gear range is selected (it varies as to what you want to do with the vehicle eg swim, climb steep hills or just drive).
The laterals are pulled back slightly to release the park locks and a slight lift in revs will get the vehicle moving smoothly. A good way to get in trouble is to rest your thumbs on the park buttons - a recipe for disaster if you accidentally engage one of the laterals in park whilst doing any real speed. Aussie 113s have little shields to prevent you accidentally pushing the buttons.

The ride of the vehicle is initially bumpy. You can feel every track link under every wheel. This soon smooths out as the vehicle picks up speed and soon becomes a background sensation, different but not unpleasant. The M113, like most tracked vehicles has a "sweet spot" in it's speed range where vibration is at a minimum and in general the vehicle seems happiest - around 25 mph. This may sound weird to a person used to wheeled vehicles but once you are aware of it, you can soon notice when a vehicle is operating in the "sweet spot". A comparison would be when a pilot in a multi-engine propeller aeroplane "synchronises" his engines - this eliminates harmonic vibrations.

The majority of most AFV crews (except all drivers and the gunners in MBTs) spend their career riding their vehicles standing up, not sitting as you would expect. Cross country standing is preferable to sitting as you can sway with the vehicle (a bit like riding a horse - you are not actually "sitting" as such, hence why they call it riding a horse and not sitting a horse). Whereas if you are sitting you usually have to brace yourself and this quickly wears you out.
Regardless, standing or sitting, cross country in an AFV is tiring. As one WW2 tank commander put it "the average person cannot imagine the sheer exhaustion from just riding in a tank turret off road - let alone fighting the vehicle". Personally, one to 2 hours in a turret cross country and I sleep very well that night!

For the driver, there is the various noises coming out of the engine bay, the roar from the exhaust and some track noise. The driving position is quite high and thus you don't get pelted with rocks as with so many other AFVs. Field of vision is excellent for an AFV. The laterals are several feet long, but despite the leverage, at slow speed you still have to use your muscles to maneuvour the vehicle as there is no power assistance. Having operated a Stuart I regard driving an M113 as luxury - it is all relative. The laterals transmit a surprising amount of feed back. When doing low speed maneuvouring you can feel each track link on the sprockets. The system allows you to position the vehicle with a high degree of precision. With a bit of experience a tolerance of 1 or 2 inches is practical for the sides and only a little more front and back with the assistance of a ground guide. Try doing that with your car!

As improbable as it may seem, when sitting in the vehicle whilst it is stationary, you can feel someone climb on the back. When moving slowly, inching really, it is quite possible to touch something (eg a gate post or small tree) and feel it in time to stop and not do any damage. Not at all what you would expect from a "tank".

Braking of the vehicle is by muscle and brute force, you just pull back on the laterals however hard is needed.

Whilst driving the vehicle you soon find yourself leaning forward with your shoulders touching the hatch rim padding. It looks a bit awkward but is easiest on the back. It also has the definite benefit that if you get things wrong and hit something solid, drop the vehicle in a hole or hit a bump, your face doesn't have far to travel to solid metal. For straight line or low speed work you can just sit upright and make minor adjustments on the laterals with ease - but beware the unexpected, shoud you be pitched forward you will make your dentist a rich man.

Over the intercom you get a background noise as the noise cancelling microphones of the headgear are only somewhat successfull. Quite often there is wind noise, speed and direction are the determining factors.

Also provided, but now ignored are another set of steering levers called the "pivots". These were incorporated into the design commencing with the A1 variant and were gone by the time of the A3 variant. They were supposed to be for better control when swimming the vehicle and for doing locked track turns in confined spaces. They were hopeless and are now just ornaments. Locked track turns exposed the driveline to stresses it was never designed to take, but as the pivot steer mechanicals were almost impossible to keep functioning without continual attention the benefit was far outweighed by the problems they caused.

On paved road the vehicle has to be operated with the normal amount of care so as to not cause any damage, much like you would if you were driving a tri-axle semi-trailer. You make your turns gentle and as wide as possible. You will notice a small amount of rubber residue (smeering) is left behind on turns as the track pads are sacrificed before the road surface.
Once you get on to sand or pasture etc you immediately know that the vehicle is in its own element, particulary in sand. It can be steered with as little as one finger. The ride is smoother and the steering more responsive, but not snappy. Where wheeled AFVs are struggling or getting bogged, the 113 trundles along happily. I note the Americans intend to replace tracked tanks with wheeled ones and get away from tracked AFVs in general, what a joke. It is obvious that the people making these decisions are desk bound experts who haven't ever been off-road in their lives.
Rocky ground is not desirable as it eats up track pads.

The Aussie Army is soon to convert our M113A1s to A3 specification which includes a steering wheel and a foot brake. A bloke I have talked to who has driven both models says he far prefers the A1 as the A3 doesn't have the finesse of control or the feed back provided by the laterals. It is easier to drive however.

Top speed is roughly 42 mph on paved road or flat solid ground. You will hear tales of higher speeds being reached, but not on flat ground in a standard vehicle. As with all things military, crews can find ways around things to "tweak" or disable settings, but usually at the expense of engine and mechanical durability. Quite frankly, without power assisted brakes, 42 mph is fast enough.

The 113 is a fairly top heavy design and off-roading must be conducted with that in mind. Attention has to be paid to all the time honoured tracked vehicle rules such as not taking slopes at an angle, the same applies with entering and exiting creeks and rivers - square on. BUT, in doing so it must be emphasised that the correct technique is essential. As the 113 is a front sprocket vehicle, any frontal impact is taken on the sprockets and thus the final drives. There is a proven weakness in the design in that the final drive casting can crack if it is hit hard - worse case scenario is that the thing breaks in half and the sprocket falls off. So when you cross a creek or approach an obstacle you do so slowly, ease up to it gently and then power on and climb the bank or obstacle. In combat, nobody cares as they have more important worries than broken final drives.

Bringing the vehicle to a stop is just a case of pulling back on the laterals. You must do this in a co-ordinated manner and by this I don't mean equal pressure on each. Take the situation where you are stoping with even a slight sideways slope: because the vehicle will want to track downslope the control required to stop in a straight line requires a different amount of pressure for each lateral. More on the lateral that is for the up slope side of the vehicle. As the speed comes off and you are down to the last few m.p.h. it is difficult to pull up dead straight. There is a marked side to side pull. I can only think that this is caused by each track link either engaging or leaving the sprockets. I don't remember feeling this with the Stuart so it may have something to do with the particular pitch of the 113 track links.

Once the vehicle has stopped you just push down on the parking brake buttons and release pressure on the laterals, they should stay pulled back. Shutting down is just a case of pulling out the engine stop handle and turning off the master switch. Before you pull the handle, the commander either confirms he is switching off the intercom or you remind him - the intercom can be spiked by the power surge caused by starting the engine.

A skilled driver can do some impressive things, such as piroettes (standing the vehicle on it's nose and turning 180), balancing the vehicle on logs or a knife edge with all its weight on only one wheel on each side etc. However the accident and breakage rate is very high with these tricks and at the end of the day, somebody has to pay the price.

The operator's manual is very specific about losing a track. On a sensibly operated and reasonably maintained vehicle this should not be a concern. However, the military operates everything to the extreme and thus the manual has to address the possibility. In essence it says that the last thing you should do is to pull on the laterals, if at all possible you should just go to zero throttle and let the vehicle coast to a stop. This sounds weird as you would expect the side with the missing track to have no bearing on the vehicle's handling. However, the manual is very specific and clear on this subject.
Pulling on the lateral(s) will result in braking being applied to the side that still has it's track and a tight turn resulting with the very real danger of a roll over. The manual states that you should only use the laterals if not doing so will result in a worse event than a roll over! eg Running over someone.

The 113 was a very sound and practical design for it's time. Most aspects of maintenance are easy. Frontal access to the engine compartment requires unlatching the trim vane and then unlatching and opening the engine bay door. Rear and side access are via the 3 large internal panels. Compare this to the FV-432 where you have to use a spanner to undo a ridiculous number of bolts, even then you are only removing small hatches. As an indicator of the excellence of the design, for it time, it is normal for a 113 crew to have finished daily servicing of their vehicle in the same time it takes an FV-432 crew to prepare theirs for servicing (clean off all the grease nipples and unbolt the engine bay covers).
The one area where the FV-432 excelled was in the fact that the engine slid out on runners and could be worked on and run whilst sitting completely out of the vehicle, an excellent idea. The more involved engine bay work on an M113 requires lifting the lid off the engine bay, the radiator is included. This is not a crew task as it requires a small crane.

In summary, the 113 is about as glamourless as armoured vehicles come. They are essentially a box on tracks. But they are a reliable, honest and pleasant vehicle to drive and their longevity in service is proof of the soundness of the design. They were supposed to be nothing more than a battlefield taxi, that idea was soon forgotten and ever since Vietnam they have been used as much as a fighting vehicle than as purely a taxi. What other armoured vehicle design is still in western use well over 40 years after it first entered service? Like all concepts it has been modified and updated.


A thank you to Alex for his input.

I am always interested in similar articles to the above for this web site.

 

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