ter herdenking 60 jaar bevrijding Zutendaal
* US M41 Light Tank "Walker Bulldog" *
14 September 2004
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US M41 Light Tank "Walker
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Picture 1 :
The waning years of World War Two found the
US tank design and manufacturing industry in full bloom, having learned much in
the preceding five years of rapid expansion. American AFV designers had taken a
quantum leap forward from their positions in 1939, and they were anxious to
develop their plans for the next generation of armored vehicles. For the
Americans, anything was possible, and there was increased interest in improving
the entire line up of light, medium and heavy US tanks even though research and
development money had dried up with post-war cuts in the budget.
In spite of the lack of funds, the once expansive design of the experimental Light
Tank T37 of 1949 began to take shape as the pared down T41. The T41 was designed
together with two others tanks as a new "family" of US vehicles, including a
"medium" tank plan called the T42, and a "heavy" tank, the T43. The T42 would
continue in development to eventually become the M47 Medium Tank, and the T43
would become the M103 Heavy Tank. With more work, the T41 would evolve into the
T41E1 Little Bulldog and eventually the M41 Walker Bulldog, named for General W.
W. Walker who died in a jeep accident in Korea in 1951.
One of the driving forces behind these new tank designs was the desire to include common
components for all three AFVs to ease their manufacture and spare parts
inventories- an honorable idea that almost did come to pass. The other strategy
behind co-designing the three new vehicles simultaneously was to simplify as
much as possible their mechanical components and operation (soldier proof) while
including similar state of the art ranging and sighting equipment.
A new vision of tank design was evolving in the US and the Walker Bulldog was one of
the best illustrations of that post-war evolution. For instance, the M41 was the
first US tank designed around a power plant, the engine finally being recognized
as one of the most important components of an AFV. Previously, a tank's general
dimensions were drawn up first and an engine then found to fit the available
space and power requirements. The Bulldog was also the first US tank with a bore
evacuator to clear the gun tube after firing (seen on the end of the gun tube in
this US Army photo). It also had an integrated fire control system to coordinate
gun laying between the commander/gunner and an automatic loader to hasten the
rate of fire and reduce the turret crew to two men. Unfortunately, due to
problems with the development of the autoloader (lack of funding), it was
dropped before production of the vehicle began. This US Army photo shows a fine
example of a M41A1, except for the blast deflector on the end of the gun tube,
which needs some attention from the crew. Notice the M75 APC behind.
Picture 2 :
This is the Part 1 of a two-part series on
the post-war M41 Light Tank. This first part will cover the basic hull
components, while Part 2 will examine the turret interior. This first image is a
cross sectional drawing of the M41 from the technical manual (TM9-2350-201-12),
illustrating the basic layout and components. As with most tanks of the time,
the vehicle is divided into three general areas- the driver's section at the
bow, the fighting compartment and turret in the center (with a gunner on the
right, commander behind him, and loader to the left), and the engine compartment
at the rear, which now includes both the engine and transmission. This was the
first mass-produced US light tank with no hull machine gun or gunner in the bow.
Instead, the space to the right of the driver was taken by a large ammo rack
containing main gun rounds (recall the preceding US Light Tank, the M24 Chaffee,
had an assistant driver/hull machine gunner to the right of the driver).
The turret and basket rotate directly behind the driver's seat and in
this drawing you can see the ready round rack on the basket floor, but further
ammo storage up in the turret has been deleted for clarity. The gun in the
Bulldog is the 76mm M32 and it is layed with different equipment by the gunner
in the M41 and M41A1, as we will see later. Notice the large turret bustle,
housing the radio gear and a large exhaust fan- the entire mass used to balance
the weight of the gun. The engine in the rear of the M41 and M41A1 versions of
the tank is a boxer-type Continental AOS 895-3 and it is seen here coupled to
the CD 500-3 Cross Drive transmission. The Bulldog was designed as a
reconnaissance vehicle, its job to slip through enemy lines, engage and estimate
the enemy's strength, and then radio back the news. It was lightly armored,
fast, and carried a significant weapon to both cause damage to the enemy and
There were over 3700 M41 Light Tanks eventually constructed and as the tank matured in use with the troops,
changes were made to improve the vehicle. This is the general arrangement of the
driver's area in the left bow of the M41 and this equipment remained relatively
unchanged until late in production. The main problem up here revolved around the
unique T bar steering crossbar; it was too weak and would occasionally break
near the right grip when yanked hard by rough handed drivers. As you can see,
the control bar rotates from mounts at the top and bottom, and the attachment
for the control rod that eventually leads back to the steering mechanism at the
stern is all the way over at the far left of the bar, attached to the hull wall.
By pushing on the right side of the steering bar the driver turned the tank left
and pushing on the other side of the bar turned the tank the opposite direction.
But, because the torque on the bar was greatest furthest from the control
connection at the far left, the right side of the bar could deform or break near
the horn button. The problem was recognized and partially fixed by strengthening
the bar from vehicle 603, and by vehicle 2453 there was a new stronger steering
bar in use that we will see in a few minutes.
A simple pull knob hand throttle is visible under the control bar's connection at the far left, and both
brake and accelerator pedals can be seen directly under the steering mechanism.
The seat is adjustable forward/back as well as up/down using the control levers
just to the left of the seat bottom (the back has been removed). The accelerator
pedal is large so the driver can still use it when he is elevated in his seat
while driving head out. A tachometer and speedometer are located in their own
small panel under the hand throttle and retaining brackets for the driver's
periscopes are at the top of the image. The driver's view outside the tank when
buttoned up is excellent, using three M17 periscopes that are angled slightly
left, directly forward, and slightly to the right, and a fourth periscope at the
far left that was angled back to the left rear.
Initial vehicles had a plan pivoting driver's hatch and movement of the inside hatch control handle
would first raise the hatch an inch or so and then pivot it over to the right.
When infrared driving equipment was added to the M41, a mount in the hatch was
included for an infrared M19 night viewing periscope to be used with additional
infrared driving lights added to the bow. The M19 had to be removed before the
hatch could be opened. The operating handle for the hatch is seen at the upper
right in the drawing, the gearshift gate is at the bottom right, and the main
instrument panel is to the far right. Regardless of the hatch type, drivers
lived in mortal fear when driving with their heads out because if the turret
rotated while they were exposed they could have their necks broken by the bottom
of the mantlet. The predominate paint used inside the M41 is typical US gloss
white and most of the darker areas seen in these images are black, including the
seat padding, instrument dials and the gear shift gate instructions at the right.
This is the image from the M41 tech. manual illustrating the driver's seat controls and associated equipment.
There is an escape hatch under his seat, and the seat bottom has to be dumped by
pulling on the release control at the back of the spring box in order to access
the belly hatch. The seat bottom is spring loaded for height adjustment, the
spring mounted in the box you see surrounded by seat controls. Simply by lifting
yourself off the seat and pulling the vertical seat control lever, the seat
bottom would rise to meet you and then lock into position when you released the
US designers gladly borrowed a number of design innovations/developments from captured WWII German AFVs, and the neat, well
protected torsion bar suspension system was an American favorite. In the case of
the M41, the escape hatch is located between the first and second torsion bars
on the floor. While torsion bars do provide a number of suspension benefits,
they also introduce problems of vehicle layout and servicing. Heavy German tank
designs required many torsion bars crossing the hull, which did not allow
spacing for belly escape hatches in most of their tanks.
Other problems inside the vehicle arising from the use of torsion bar suspensions is the
additional height required of the hull for the equipment and the more difficult
servicing of broken components. The cable looping down at the upper right of the
picture is from the hand throttle, while the connecting rods below the throttle
cable are from the accelerator pedal and gearshift (range selector). This fire
extinguisher is a red 5lb CO2 type and it is portable. The engine compartment is
protected by two 10lb fixed cylinders and an automatic fire suppression system.
Another image from the M41 manual illustrates some of the equipment immediately to the right of the driver.
The gearshift gate allows automatic shifting from two forward ranges (low and
high) as well as one reverse range. The single stage hydraulic torque converter
allows very smooth gear changes, although there is a bit of slippage at low
speeds. We also begin to see further interest in crew comfort in this US M41
design with the inclusion of a built-in crew heater; the heater duct and
controls are at the bottom and far left of the illustration. The periscopes are
not installed, but you can see the holding clamps for the right periscope at the
top left of the picture. The early hatch release control handle is also visible
up there, to the right.
In the center of the instrument panel are a number of indicator lights, and the instruments underneath include left and
right fuel level gages and the engine oil pressure gage. The large black
electrical switches include the main driving lights (left bank of switches) and
the main engine power switches. The M47 Medium Tank and M103 Heavy Tank use
almost identical primary instrument panels. An auxiliary generator gasoline
engine is located in the rear engine compartment and allows power for recharging
the batteries as well as lights and other electrical requirements when the main
engine is switched off; the controls for the aux. generator are at the far left
on the panel. The auxiliary power outlet receptacle (above) allows power
connections between vehicles to assist start them when they have dead batteries
or other electrical problems. Although we do not see it in this image, the area
of the bow to the right of these panels is filled with horizontal storage tubes
on a multi-tiered rack for 76mm main gun ammo.
This image of a late M41A1 comes from the same tech. manual (it covers both vehicle types) and illustrates
the improved steering T bar and the installation of the infrared periscope M19.
Most of the other equipment is identical with what we saw before, but notice
that the M17 periscopes are now installed and the retaining clips are locked
closed. The introduction of infrared lights and viewers on the Walker Bulldog
was a big step forward for the US Army. Although research into infrared viewing
devices had been occurring in the US during the last years of the war, the
capture of German equipment and information provided by German scientists
accelerated the program greatly.
Initial post-war US tanks used infrared as a driving aid only because the lights were dim and the beams did not carry
far. Tanks were fitted with these smaller infrared driving lights at the bow of
the vehicle, next to the traditional service headlights and blackout lights. It
was only later that powerful infrared searchlights were mounted up on the turret
mantlet, which allowed direct targeting at night. Infrared lights produce a very
short wavelength light that, in its pure form, is not visible to the human eye.
The simplest infrared viewers, like the M19 here, collect the reflected IR rays
and use an image converter tube to change them back to visible images that are
seen through the eyepieces.
The periscope consists of two main components- a quickly replaceable head assembly that contains the prism to
direct the reflected infrared rays down to the periscope body, and the body that
contains the objective lens and image converter for the reflected rays. The
viewer requires electricity and you will usually find a power plug for the
periscope in the vicinity of the viewer, in this case off to the right.
Magnification through the M19 viewer is only 1x, which relegates the periscope
to the driver's position in most AFVs. By the way, this same M19 periscope, in
one form or another, is still used today by the US Army and a number of other
countries, typically in the improved M19A1 form.
Picture 7 :
When the access plates are removed, the hatches fully opened, and the hatch support bracing is removed, the engine
compartment looks like this. The Continental engine is an air-cooled,
6-cylinder, opposed, and supercharged gasoline engine. Air cooling does away
with liquid coolant systems and their propensity to leak or rupture, but it
requires very large fans and many cooling ducts and vents. The black fan and
shroud is located at the forward end of the central compartment, and just about
covers the entire engine. Off to both sides of the engine you can see the
insulated exhaust pipes leading to the mufflers on both side fenders- these are
not "cooling" vents as indicated in the legend but the exhaust pipes are covered
with protective cooling jackets.
To the upper right of the bay (right/forward) is the top of the auxiliary engine/generator. Also on the right,
but further back toward us, are the batteries (24V DC system). The white painted
transmission case occupies most of this end of the compartment and is covered
here with shifting linkages and other controls. Cross Drive transmissions, like
this Allison CD-500-3, combine the transmission and steering unit into one box,
providing a very compact package for armored vehicles. This same power shift
transmission design is also used in other vehicles that share the same general
chassis components of the M41, such as the M44 and M52 SPG and the M42 SPAAG
(Duster). This transmission's big brother, the CD-850, has been used in a number
of larger vehicles, including the US M48 and M60 tanks as well as the first Israeli Merkavas.
The engine/transmission in the M41 is loud... VERY loud, and anyone standing near it when one of these monsters opens up in first
gear will not soon forget it. Each gear has its own characteristic sound, from
the load scream of first gear to the whining of the others. The exposed mufflers
on the fenders become so hot they glow in the dark and extreme care is required
when working around these areas to keep from burning yourself.
Picture 8 :
This is the training manual image of the Continental engine when attached to the Allison transmission- the left picture
is the left side of the engine. This was one of the last gasoline power plants
to go into a US armored vehicle, as diesel power would shortly become recognized
by AFV designers to be necessary to increase the range available for a given
amount of fuel. The AOS-895 displaced 895.9 cubic inches and delivered 500 gross
horse power at 2400rpm. With the approximately 140 gallons of gas in its tanks,
the M41 has a cruising range on roads of only around 100 miles, and roughly 2/3
of that on cross country conditions. However, on those same roads, the maximum
speed was over 45mph, so although the range was limited, this was one fast
little tank for its time. In order to improve the vehicle's range, the
carburetors were replaced with fuel injectors, and the M41s powered with the new
engine were renamed M41A2 and M41A3, respectively.
Because the M41 was designed to be robust and simple to maintain, it proved popular with a number of
country's Armed Services. So when the vehicle was withdrawn from US active
inventory with the introduction of the replacement M551 Sheridan, surplus
Bulldogs were given/loaned/sold to many countries allied with the USA. This is
another US Army photo, in this case showing Thai troops learning transmission
servicing from their American instructors in 1962. Although the lower rear
transmission cover is still closed, the upper one is hinged open and a number of
the smaller side access doors are also opened. Notice the engine oil filler neck
and its corresponding port in the upper transmission access cover. If you look
closely, you can see both the range selector control rod and the gear changing
rod traversing across to the top of the transmission from the left hull wall.
The batteries are barely visible on the far right as well as their retaining
bracket. Although the interior of the engine compartment was painted the same
gloss white as the fighting compartment, the inside of the engine hatches are
the primary exterior color, in this case some shade of olive drab green.
The primary difference between the M41 and M41A1 is the gun laying equipment inside the turret. The
controls to elevate/depress the gun and rotate the turret were changed during
early production in order to comply with a new Army Field Force directive in
1951 (after the tank had been in production). The directive required that only 5
seconds would be necessary to fire the gun after the decision to engage a target
had been made. For that day, 5 seconds to select ammo type on the ballistic
computer and traverse, elevate or depress the gun onto target was very quick
indeed, and the initial pulsing relay control gun laying system was not equal to
the new requirements.
In order to comply with this new directive, the primary manufacturer, Cadillac Motors of GM, designed a modified turret and new
gun control system, and these were introduced into production line on vehicle
1419. The new Cadillac system turned out to be quicker, less complex and
occupied less space than the original pulse relay system, and after experimental
usage in a number of different vehicles, the Cadillac system and new turret
became standard issue from tank number 1803 on. Prior M41 tanks were also
supposed to be converted to the Cadillac system, but improvements to the
original pulsing relay control allowed it to conform to the 5 second order, and
those earlier vehicles were modified with the improved pulsing relay system
instead. The tanks with the original turret type and improved pulsing relay were
left with the original M41 designation, while those later vehicles with the
modified turret and Cadillac system were named M41A1. You will find both vehicle
types in photos of the US Army, as well as a number of other armed forces around
the world, sometimes side by side in the same unit.
The left image here is the M41 early turret type and the one on the right is the M41A1 later type.
When you examine the turret sides of the different vehicles in these US Army
photos you will see that the M41 turret (left) uses more cast armor, including a
band along the lower area of the turret side. The M41A1 type has cast armor only
on the front of the turret and there is no visible weld seam along the lower
area of the turret side extending to the rear bustle. Of course there were also
changes to the gun mount and interior of the turret, but we will explore these
and other internal components in Part 2 of the M41 Walker Bulldog story.
The original pulse relay gun laying system in the M41 allowed both manual and power controls for the gunner as well as override
control for the commander in both elevation and traverse. It was a remarkable
system, but unfortunately, as we discussed in Part 1, it could not meet the
requirements of a new 5 second "locate target and shoot" directive, so an
"improved" pulsed relay system was developed and installed in all M41 type
vehicles. In a nutshell, the improved pulsed relay system provided only manual
hydraulic elevation for the gunner as well as power and manual traverse of the
turret. While the tank commander could operate the power traverse with his
override control, he could not elevate the gun. This improved system did meet
the 5 second rule, but limited the ability of the commander to fully operate gun
laying and confined the gunner to manual elevation.
This is the technical manual illustration of the improved pulsed relay gun laying system at
the gunner's position in the M41. To elevate and depress the gun tube the gunner
hand cranked a hydraulic pump at his left, which would pressurize a hydraulic
cylinder attached to the gun cradle. Rotating the pump handle in one direction
raised the gun and rotating it in the other would lower it. Although it was
called a "manual" system, the hand crank was still hydraulic assisted, and was
therefore actually a hydraulic powered system, in contrast to an electric power
system. The word "powered" when used to describe AFV gun laying is confusing, as
some sources and manuals regard powered as having any type of boost assist,
while others refer to only electric motors as "powered". The general consensus
has been that when a control has to be hand cranked it is "manual" and when it
only has to be moved in one direction or another it is "powered", as something
else is actually doing most of the work. It is helpful when referring to powered
systems to indicate the type of assist, whether it is oil hydraulic, electric,
or a combination of the two. Strictly speeding, manual systems should refer only
to mechanical manual, where there are only gears and hand wheels to move the gun
and turret, but the definitions have become blurred over the years and now
manual means any control which requires pumping or turning (work) to activate.
Recall when studying this picture that the commander could not control gun
The gunner's elevation ("manual") hand crank is difficult to see in this image, but it is at the left side of the picture, under the
telescopic sight, near the label "F". To traverse the turret the gunner had the
option of using either a manual hydraulic crank pump, in this case seen as "C"
in the picture, or he could use an electric hydraulic system via the black hand
grip you see as "K". This system uses electric contact switches to activate a
motor under the turret basket, which then rotates the turret.
For years US tank designers had shied away from electric motors for turret traverse and
gun elevation for a couple of reasons. The first was its reliance on power
generation and electricity. Dead batteries were a way of life for tankers during
WWII and if your electric power went out you were then dead. Therefore, electric
motors for gun laying were considered too unreliable in AFVs until late in the
1950's/early 1960's. But, perhaps more importantly, hydraulic motors had served
American tanks (as well as US industry) very well in the past, and a hydraulic
motor was far more powerful than an electric one of the same weight and size at
that time. Of course, hydraulic power still required an electric motor, or small
internal combustion engine, or even a hand pump, to compress the hydraulic fluid
so it could do its work. But tank design officials believed that pound for
pound, hydraulic motors provided more power and were more reliable than heavy
electric motors for moving guns and turrets. This belief still reigns today in
the US where most turret movement controls are still hydraulic powered, or have
a hydraulic back up system to the electric motors.
There are many other important pieces of equipment visible in this illustration. The gunner's primary
sight is the over-head M20 periscope. It is both a wide angle periscope and a
gun sight with lighted reticle, and it is linked to both the gun cradle and the
TC's identical M20 in his cupola, so both tankers have the same sight view. The
periscopes and gun are linked at a small box called the Ballistic Drive M4. Here
it is seen on the ceiling of the turret to the far left ("A"), and shows a
series of range scales that have to be calibrated for each type of ammo round.
You can think of the ballistic drive as an early computer for figuring the
correct trajectory for ammo type and target range from the tank. The telescopic
sight M97 at the left was strictly a backup sight, as the field of view was
considered too restricted for normal operations and you could hunt for days just
looking for your target. On the other hand, Americans are very fond of their
back up sights, as they hate to be in a killing machine the size of a tank and
not be able to fight due to the primary sight being temporarily out of action.
The white box at the upper right is the gun firing control box (an electric
switch panel for energizing parts of the gun laying system) and the traditional
black azimuth indicator is located below on the turret ring with its cylindrical
light battery mounted to the turret wall above it. The 76mm gun is just out of
view to our left.
This is the arrangement for the revised
Cadillac gun laying system found in M1A1 vehicles. Much of the equipment is the
same or similar as the pulsing relay in the M41, but now the odd hand wheel in
the center of the picture controls the power turret traverse (an oil gear power
traverse). Rotating the wheel clockwise traversed the turret to the right while
counter clock wise traversed the turret to the left. The manual traversing hand
crank is to the right, between the powered traverse control and the azimuth
indicator. To the left of this equipment is the gunner's manual elevation hand
wheel. The commander's traversing hand control is visible at the upper right in
the photo. Recall that he could also elevate the gun using an electric slewing
motor and his controls overrode the gunner's in an emergency.
members have the same M20 periscopes for viewing and targeting that we saw
before and both are visible in this photo, showing the sighting eyepiece to the
lower right of the periscope as well as the 1x unity window at the bottom. The
76mm gun is better viewed in this photo than in the previous, with its vertical
semi-automatic breech now clearly visible. The weapon was fired electrically by
the gunner via a thumb button on the elevation wheel. Notice the gunner's seat
and the protective screening at the front of the turret basket to keep him from
banging toes as the turret traversed. The screening was installed only around
part of the basket as some of the main gun ammo was stored in the space to the
right of the driver and had to be retrievable.
Picture 13 :
A closer view of the upper area of the Cadillac gun laying system shows a few more details. The ballistic drive on the
ceiling is similar to the one used in the M41 and you can see the control knob
for setting ammo type and range. A small power switch is on the right side of
the case. The close proximity of the M20 periscope and the M97 telescope is also
clear in this image, and the power traverse hand wheel dominates the bottom of
the image. Notice the rubber padding around the viewers of both sights to
protect the gunner's eye and face. There was no stabilisation for the gun and
the vehicle had to come to a halt to fire accurately. Half of the hand elevating
wheel is at the lower left and the electrical control box for the gun laying
system is at the upper right.
The thin connecting rod rising from behind the traversing hand wheel to the upper right, and then connecting to a cross rod
running towards us, eventually ends at the commander's hand control (just out of
view over our heads) for traversing the turret. Notice that the gunner's
mechanical hand traverse control is visible at the lower right corner. One of
the worst problems with the ballistic drive and the periscope sights in early
set ups was that their connecting actuators were attached to brackets on the
ceiling of the turret. When the roof heated up and expanded in the sun, it threw
off the alignment of the sights and gun, so later M41 and M41A1 vehicles were
provided with an improvement kit that attached to the devices without support
from the ceiling.
The first M41 tanks used a .50cal Browning machine gun for a coaxial weapon on the left of the main weapon, but most
vehicles later used a .30cal instead, and the early tanks were modified to the
.30cal standard as time went by. The .50cal was originally included to provide
improved firepower against soft skin vehicle targets in order to save main gun
rounds. But when the actual use of the MG was evaluated, and the increased
amount of ammo that could be carried for the smaller .30cal was considered, the
.50cal coaxial was replaced with the smaller MG.
This image shows some of the detail to the left of the 76mm gun that is the loader's cramped corner of
the turret. Ready round racks for vertically stored 76mm ammo are seen on the
floor and wall and an ammo box for coaxial .30cal rounds is clear at the front
of the turret. The 76mm ready rounds sat on rubber rings inside cups that held
the face of the shell casing and the rack clips you see have quick release
latches, opened by a toggle on the bottom of each latch. The loader's safety
switch (ready button) is located in the white box to the upper left in the
picture, and the black breech of the main gun is to the bottom right. The gun
has a concentric spring hydraulic recoil system that surrounds the gun tube just
forward of the breech block; the cylinder seen on the gun recoil case at the
left houses a spring to assist opening/closing the semi-automatic breech.
Semi-automatic breeches open automatically after the gun is fired and eject the
spent shell, allowing the loader to just shove home the next round without
having to open the breech himself. A small part of the loader's recoil shield is
also seen just to the left of the breech.
Picture 15 :
This is the floor of the early M41 turret with horizontal ammo storage tubes and the vertical storage pads for the ready
rounds at the bottom of the picture. This is the loader's floor area, with the
main gun pointing to the left of the picture and the loader's seat in the up and
stowed position to the right. The M41 could only house 13 rounds in this
horizontal rack, due to space taken by the pulsing relay box and other gear on
the floor. Nine of the rounds were protected in individual sheet metal boxes and
four others were laid on top and retained by clips at this end of the shelves. A
large bin for stowing MG ready round belts is at the far left. The spent
cartridge bin was a sheet metal collapsible unit at the back of the turret
floor, and when opened like it is in this picture, was held open with a latch on
the floor you see here. The gunner sits up fairly high in the turret and his
metal footrest plate is at the left, above the horizontal ammo rack. Although
not seen here, a shell deflector plate was attached to the back of the turret
basket (at the turret ring) to deflect ejected cartridges down into the bin.
Along with the 13 stowed rounds in the horizontal rack, the M41 also
carried 11 rounds in the vertical ready round racks closest to us and another 33
in the hull rack to the right of the driver. The front rack was not accessible
during normal operations and the turret had to be rotated in order for the
loader to retrieve new shells to refill the horizontal and ready racks. The
pulsing relay box is seen at the center of the floor and the electrical turret
master control box is just behind it, mounted on the side of the hydraulic
compressor housing. With the use of the Cadillac gun laying system in the M41A1,
the hydraulic equipment was reduced in size, and additional floor space was
provided to allow additional horizontal racks on the floor, for a total of 21
rounds instead of the 13 in this M41.
Picture 16 :
Another view of the collapsible 76mm spent cartridge floor bin also gives some indication of the equipment at the back of
the turret basket. The M41 style bin is again in the open and locked position
and the turret electrical control box is now immediately to the bin's left. The
spent cartridge deflecting shield is now visible above the bin and behind the
gun breech, and one of the two 10lb CO2 fire extinguishers for the engine
compartment is visible at the far right. The engine compartment fire suppression
system relied on heat sensors and extinguisher chemical nozzles placed at
strategic points to douse fires when the system was activated. There were manual
pull controls also, one located up by the driver and one on the exterior hull of
the vehicle for use when outside. As of this time, there was no automatic system
for the crew compartment, the portable 5lb extinguisher we saw earlier was all
that was available for interior crew fires.
The two cylindrical air cleaner cans for the engine were also mounted here on the firewall, but to the
outside of the fire extinguishers and out of view. Ducts took the cleaned air
back to either side of the engine and to the carbs. The loader's stowed seat is
at the upper right and the commander's is across the turret from us, at the
upper left. It has a simple plywood seat bottom padded with foam rubber, covered
with black imitation leather, and adjustable in height. Under the commander's
seat is the domed case of the turret power pack (electric motor) and the height
adjustment lever for the commander's seat is just visible above the power pack.
Picture 17 :
The spent cartridge bin mounted on the floor of the M41A1 was different and more substantial than the folding one in
the M41. This image of the M41A1 floor shows the black bin open and locked and
you can make out the hinges at the far right and the locks to keep it open on
this side of the bin wall. When closed, the back pivoted over and down, making
just a two inch high platform on the floor. Across the turret is the gunner's
seat with its special height adjusting mechanism underneath. The top of the
larger horizontal 76mm ammo rack is now at the left in the image. In this new
arrangement there are individual shell boxes stacked on the floor as before, but
now there are 14 and shelves above for another 7, all in a similar style rack as
we saw before. Combined with the same sized ready round and forward hull racks
as the M41, the M41A1 could carry a total of 65 rounds, compared with the M41's 57.
The 76mm gun fired a number of different rounds over the years, the
most common in US service were the AP-T M339, HVAP-T M319, the HVAP-DS-T M331A2,
the HE M352 and the canister round, M363. I believe these are all bras cased
rounds, with the exception of the M331A2, which was steel. The M339 is a APBC-T
shot, the M319 is a APCR-T, the M331A2 is a APDS-T and the HE M352 is a high
explosive shell. In addition to these rounds, the Walker Bulldog carried around
5000 rounds of .30cal (for the later coax MG) and up to 600 rounds of .50cal for
the AA MG carried up on the turret roof. In the turret were also carried a
.45cal Grease Gun with ammo and usually a .30cal carbine for the driver.
Picture 18 :
This is the right side view of the M32 76mm high velocity gun used in the M41 and M41A2, but installed in the M76A1 mount
used in the M41A2. There were only a few differences between the mounts. The
elevating mechanism and hand wheel are the most obvious as the earlier M41 used
the pulsing relay system with the elevation hand crank located on the motors
directly in front of the gunner, not on the gun mount as we see here. Notice
that the elevating gear that is attached to the roof of the turret is protected
by a rubber boot. Just a bit of the concentric recoil is seen surrounding the
gun tube, this type of recoil mechanism had become very popular when tight
interior conditions were expected and there was no room for bulky recoil
cylinders on the sides of the mount. The recoil shield on this side is very
large to protect the gunner and the TC from having their left leg or arm broken
from the recoil of the breech.
The M32 gun could hurl a 15 pound AP shot down range at 3200fps, or even faster with hypervelocity armor piercing ammo
(HVAP). Maximum rate of fire was said to be around 12 rounds per minute and
maximum range was greatest for this type of round, nearly 23,000yds. Effective
range was limited to less than 2,000 for anti-tank hunting due to the gun
accuracy, but this was more than sufficient for killing T-34/85s that were
expected to be the main target for this tank. When the Soviets produced the T-55
with its increased armor and bigger gun, the Bulldog's gun was outclassed, and
something bigger had to be called upon to deal with the new Soviet "threat".
Picture 19 :
From the top of the M41A1 we can see the arrangement of hatches and other equipment. The commander's cupola on the right
side of the turret roof is non rotating and contains five vision blocks as well
as his M20 sight. The inside of his hatch has no padding and only a simple latch
handle to keep it closed. The .50cal Browning is pintle mounted to the left and
slightly forward of his hatch, and it is in an awkward position for rear facing
anti-aircraft work, but well placed for forward fire support. The loader's hatch
is angled on the left side of the turret roof, and hinges open forward to
provide some protection from the front when partially open. It is padded on the
inside surface and also has a simple hand latch inside to secure it when closed.
The loader is provided with a stationary M13 or M13A1 periscope just forward of his hatch.
At the back of the turret bustle is the exhaust fan dome and
the traditional crew storage box is affixed to the back of that, extending the
rear of the turret almost to the back of the tank. Some of the driver's hatch
and periscopes are also visible, including the rotating M19 infrared periscope
mount in his hatch and the one M17 periscope that faces left and slightly to the
rear. On these later turrets the three antenna bases wee all on the left side,
and they can be seen just forward and to the left of the loader's hatch, behind
it some distance, and back by the exhaust fan. Armor on the Bulldog was very
thin, ranging from 1.25in (32mm) on the front hull and mantlet, to 1in (25mm) on
the hull and turret sides, to .05in (13mm) on some of the rear armor. It was
designed to be proof against .light MG rounds and shell splinters, but not much
The large turret bustle of the Walker
Bulldog was designed especially for extensive radio equipment, as the recon
vehicles were expected to patrol behind enemy lines far from other ground units
and still communicate effectively. Most American M41/M41A1 tanks of the early
Cold War period used one of a number of AN/GRC-3 through AN/GRC-8 radio sets.
During this time, the -3 and -4 were usually armor unit radios (20.0-27.9 MHz),
the -5 and -6 were artillery (27.0-38.9 MHz), and the -7 and -8 were infantry
(38.0-54.9 MHz). Because there was overlap in the frequencies used by each unit
type, it was possible to contact support units with your own radio on most
occasions. Notice that infantry could call for artillery support and armor could
call in artillery, but armor could not call infantry and vice versa using this set up.
The interphone included inside had provisions for hookups for
all four crew members as well as an extension kit for a rear plate mounted phone
for conversation with support infantry, just outside the vehicle. In this set
up, the interphone radio box is an AM-65/GRC type and is located to the far
right. Notice the connecting cords at the bottom of the unit that would lead to
each crew member's radio connect box at their station. The "A" set above is
probably an RT-70, which is a receiver/transmitter with continual tuning or two
presets and operates on FM in the 47-58MHz range. To the left of the RT is a
PP-112/GR power supply, taking power from the battery hookup at the lower right
and amplifying it for the "B" set you see to its left. The "B" set could be any
of three different units, depending on the frequencies needed and the units the
tank was assigned to, but usually it was an RT-66 or 67 or 68. She was packed
with 27 tubes and was also an FM radio. At the far left is the partially hidden
receiver, again one of three types depending on mission. Under the mounting
shelf is the main control box for the radio set.
This was a time when radios became increasingly complicated as their capabilities were stretched to
new limits and tank crews became as much experts on radio communication gear as
they were with their mechanical horses and guns. This was not a situation
particularly welcomed by tankers, and it would take years before radio design
would again emphasis simplicity and ease of use. But first, technology would have to catch up.
As you've seen, the M41 Walker Bulldog was a remarkable little tank for a number of reasons, not the least of which were its
basic design improvements. The Americans did not get the chance to use the light
tank in any large-scale actions, as it appeared too late for Korea and too early
for Vietnam. But it has had the opportunity to show its worth in other country's
inventories, fighting in India-Pakistan, Vietnam with the South Vietnamese, and
countless other battles and skirmishes. But by the late 50's, something new was
on the drawing boards for light armor in the US Army, and that something new
would cause some of the worst controversies within and outside the military that
had ever been seen. As the role of light armor was debated and changed, it was
lost entirely as US planners searched for one vehicle that could do it all.
Met dank aan Marc Geurts.