And so we continue with the assessment from the ETO from last week of the various vehicles they received, and some picks of the more interesting or surprising issues that were commonly encountered. Again, occasional Chieftain provided for scale.
Tank, Light, M24
Number in hands of troops: 3,330.
General: This vehicle was well received by using personnel who particularly liked its maneuverability and armament. The M24 Light Tank has been a reliable vehicle during long road marches and combat operation. However, many minor design changes have been requested by the various units which did not basically affect the overall performance of the vehicle.
Pump, fuel, electric: Fuel strainers located in the fuel tanks were not effective enough to prevent foreign particles from entering the carburetor. Late models had a horizontal filter mounted at the carburetor which minimized foreign particles entering the carburetor.
Hub, track wheel: Nut, lock, track wheel with flange assembly continuously worked loose and required constant tightening daily. Since both track wheels are mounted side by side, the truck type nut, locking, should replace the present lock mount.
Accelerator and throttle control assembly: Many cases of poorly performing vehicles due to the engine not being properly synchronized were experienced. Improper adjustment of the throttle linkage was the cause of this malfunction.
Door, driver’s and auxiliary driver’s: Early model tanks did not incorporate a door handle by which the driver and auxiliary driver hatch doors could be readily lifted from the outside. Ordnance Technical Bulletin #72 of 05Jun45 authorised and outlined the installation of door handles on these early tanks.
Support, track roller. The rear bracket mounting the track support roller failed when the the track was not properly adjusted. These failures occurred when the track was loose which allowed the track to whip over the rear idler onto the support track roller. [Chieftain: See? I keep harping on about track tension…]
- The direction of the exhaust should be changed as many units complained that during dusk or night operations the flame from the exhaust would shoot skyward and be readily detected by the enemy.
- It is recommended that an auxiliary generator with a declutching device be considered for future production. Light tanks when used as outposts continually experienced battery difficulties since radio operation was mandatory whereas it was impossible to use the main tank engine for security reasons.
Carriage, Motor, Gun, 90mm M36
Number in hands of troops: 1,080
General: Tank destroyer units that were issued these gun motor carriages after firing the M10 GMC had favorable reaction to this piece of equipment, both from the standpoint of mechanical reliability and its increased armor and firepower. Tank destroyer units were call upon to furnish direct fire on pill boxes and other fortifications in addition to indirect firing missions. In fulfilling the direct fire role, the M36 GMC, because of its heavier armor and increased fire power, was usually assigned this mission.
Cooler, transmission oil: Transmission oil coolers were damaged by extracted cartridge cases. The slatted guard provided over the oil cooler weas very weak in construction. The extracted cartridge cases would hit the slats and smash them back against the oil cooler core. The slates would brake and allow the ends of subsequent cartridge cases to strike and penetrate the core. Using units were instructed to add extra slats in the guard thereby closing the opening between the slats.
Lock, turret traversing: Turret locks failed due to the shearing off of the four cap screws attaching the turret block to the turret ring. The added weight of the 90mm gun and the counter-balance overloaded the turret lock to such an extent that the cap screw was of insufficient size to carry the load. Units were instructed to drill and tap the turret lock and turret ring to install a 5/8” diameter cap screw.
Tank, Heavy, M26E3
Number in hands of troops: 300
General: The M26E3 heavy tank arrived in this theater during the latter stages of the European Campaign. It was received with enthusiasm because of its superior fire power. However, as troops fought with this tank several outstanding disadvantages were experienced by them, such as insufficient armor protection and reduced mobility. The vehicle, after proper servicing upon arrival in the theater, performed fairly reliably. Many small deficiencies were encountered which should be remedied in any future production.
Regulator, Voltage. Regulators failed due to points fusing on the voltage control and on reverse current relay. The cause for failure has not been ascertained. Maintenance units have not been supplied with TMs, consequently little is known about the function of this type regulator. It is recommended that this difficulty be further investigated, if possible from the standpoint of unsuitable material in the regulator points. It is further recommended that fourth and fifth echelon maintenance personnel be informed of the proper maintenance and tolerances for this regulator.
Lock, Track Drive Sprocket Bolt: The bold holding the drive sprocket to the hub worked loose and sheared off. It is recommended that these bolts be of larger diameter.
Miscellaneous: Using organizations had the following recommendations to offer for basic design change:
- The fuel capacity of the vehicle should be increased to allow a greater cruising range. Many units believed that the cruising range of this vehicle should be double its present range.
- Larger escape hatches should be designed into this vehicle.
Engine, Ford, Models GAA and GAF
Number of engines in service: 4,350
General: Even though there was a dearth of replacement parts available to field maintenance units, this engine served well and reliably during combat operations. Using personnel preferred this engine to the air cooled radial type engine because of its higher horsepower and torque outputs.
Block, engine cylinder. Rod, Connecting engine: Twenty-five percent of the engine blocks processed in base shops were scrapped due to holes in the sides caused by broken connecting rods being thrown through the block by centrifugal force. This damage was the result of low or no oil supply or overspeeding the engine. The small percentage of engines equipped with the new type oil pan containing the two compartments and two oil pump screens returned to the base shop for overhaul were unserviceable due to fair wear and tear. High oil consumption was an undesirable characteristic of this engine, therefore it is recommended that the crank case oil capacity be increased, a signal device be incorporated to warn operators of approaching low oil supply, and that a dry sump oil pan with adequate scavenging action and oil tanks for at least 12 hours operation be installed.
Crankshaft: It was necessary to scrap 35% of the crankshafts of engines returned to the base shop for rebuild because the journals were scored so badly that they could not be reclaimed by regrinding. It is recommended that improvement in engine design to reduce bearing failures be considered.
Gasket, Cylinder Head: Many cylinder head gaskets on new engines were blown out due to cylinder head studs not being tightened to the proper torque tension during assembly. A considerable number of engines examined revealed that the cylinder head studs were only slightly more than finger tight.
Belt, Fan: Fan belts failed due to the following causes: i) Belts were not in matched sets. After a few hours of operation, one belt stretched longer than the other, throwing all the load on the shorter belt. ii) Improper belt adjustment. iii) When the engines of vehicles received at the ports in this theater were started, the suction of the fan pulled the silica-gel bags through the sheaves and cut the fan belts into shreds after a few hours of operation. Combat vehicle servicing crews at the ports were instructed to open all the engine compartments and remove silica-gel dehydrant bags before starting the engine.
Engine, Continental, R975-C1 and R975-C4
Number of engines in service: 5,283
General: this engine performed fairly reliably, however, engine life was considerably shorter than desired during offensive operations. In most instances this engine was under-powered for the vehicle in which it was installed.
Engine: Many engines failed due to hydrostatic lock. Engines frequently developed hydrostatic lock after standing idle for only a short period of time. This failure occurred with experienced operators who were all well trained in the proper operation of the air-cooled radial engines, and therefore could not be traced to negligence or ignorance of the driver. In all cases engines started with hydrostatic lock resulted in bent (and in extreme cases, broken) master connecting rods and broken cylinder heads. Tank crews were instructed to clear all radial engines before starting. It is recommended that oil tanks be positions so that oil cannot flow back through oil pumps into the engine crank case and that scavenger pumps and oil pumps be of sufficient capacity to clear the engine of all oil during the 5-minute idle period before stopping the engine.
Many tanks have caught fire due to oil and gasoline leaks developed around engine cases, accessory mountings, and oil and gasoline unions. The characteristics of the engine are such that oil is blown out through the crankcase breather covering the cylinders and exhaust manifolds after piston rings have started to wear and create a blow-by. This condition created a dangerous fire hazard. Using units were instructed to keep all fuel and oil line unions tight and change engines when they started to blow oil out through crankcase breather.
Truck, Trailer, 45-ton, Tank transport M19. Truck, 12-ton, 6x4, M20.
Number in hands of troops: 901
General: The M19 tank transporter, even though originally designed for the British Army, was extensively used in this theater by US troops. This vehicle did not meet the overall requirements of this theater, and was necessarily assigned for duty in the rear areas of the combat zone, and Communications Zone. The large turning radius, the poor traction of the prime mover, and the high road resistance were major deficiencies of the M19 tank transporter.
A trailer, M9, was redesigned as a semi-trailer, and a truck, M20 was converted to a truck-tractor by the removal of the body and installation of a fifth wheel. The net weight of the unit was decreased by approximately 3,000 pounds, but the biggest reduction in road weight was the elimination of the five 2,000-pound concrete blocks that were carried in the M20 truck to obtain adequate traction. Performance of the converted unit under actual operating conditions indicated:
- 50% increase in fuel economy
- Adequate rear wheel traction of the truck-tractor for satisfactory operation over first and secondary type improved roads.
- Unsatisfactory operation on deep muddy roads, and cross-country under adverse weather conditions. However, the converted unit did not ‘bog down’ as quickly as the standard design.
- Less gear shifting under road operation.
- 15% reduction in turning radius.
- Less driver fatigue
Evacuation company crews felt that the vehicle was fairly reliable, but commented adversely on its awkwardness in operating through towns, on narrow highways, and when in reverse. Because of this, they preferred the M25 truck transporter even though it was wider. The crews which operated the converted M19 unit preferred it to either the regular M19 or M25 tank transporter.
This office is of the opinion that all tank transporters should be truck-tractor semi-trailer combination, the maximum size being that of the present M25 design. Temporary bridges, inferior roads, extremely narrow streets in old villages etc., prevalent in European countries definitely prevent satisfactory operation of extremely large over-the-road vehicles.
Landing Vehicle, Tracked, MkII, and IV
Number in hands of troops: 468
General: the Landing Vehicle, Mk II and IV performed satisfactorily under actual operating conditions. Very little trouble with this vehicle was reported to this headquarters. Considerable modification was performed on these vehicles, such as installation of armor, 75mm howitzer, etc. Personnel operating these vehicles were satisfied with its performance and reliability.
Truck, Trailer, 40-ton Tank Transporter M25. Truck Tractor M26
Number in hands of troops: 726
The M25 Tank Transporter has been a fairly reliable vehicle even with the lack of proper first and second echelon maintenance services. Generally, the using personnel was satisfied with its road performance, but expressed the desire for a truck-tractor – semi-trailer combination that would be narrower and shorter in overall length. Evacuation companies assigned to Armies preferred the armored cab while Communication Zone units had preference for the “soft top” unarmored cab.
Carrier, Cargo, Light, M29 and M29C
Number in hands of troops: 2,660.
General: During the early stages of the European campaign, the M29 carrier was placed in inexperienced hands with a very minimum period of training before D-Day. Consequently the vehicle was abused and used beyond its design limitations. It was not uncommon to observe these vehicles being operated over hard surfaced roads at speeds in excess of 40mph. The M29 Cargo Carriers rapidly become unserviceable due largely to ignorance or unwarranted abuse by using personnel. During the later stages of the European Campaign this vehicle was used as a special purpose vehicle as intended. The educational program by the M29 Cargo Carrier instructor teams did much to improve conditions in using organizations. This vehicle when used for its intended purpose gave satisfactory and reliable performance.
Hull: Many hulls were damaged due to too light construction when pushed by another vehicle. It is recommended that the installation of a bumper be considered for future production.
Truck, Amphibian, 2 ½ ton, 6x6
Number in hands of troops: 1,550
During the early stages of the European operations, these vehicles were relied upon for getting supplies from the ships to the shore. Generally the troops operating these vehicles were not well trained in the proper operation and preventive maintenance necessary for long reliable life. This Headquarters continuously insisted on the second echelon inspections, but due to the pressure exerted on the DUKW companies by the Port or Beach Commander to get critical supplies ashore, adequate servicing was sacrificed. Many vehicles were deadlined primarily due to lack of second-level maintenance service. The personnel of the using organisations were satisfied with the performance of the DUKW and had very little criticism to offer in the way of major redesign for more satisfactory performance.
Engine governor: Governors were not tamper-proof enough. Many cases were discovered where the butterfly in the governors had been completely removed, thereby eliminating governor action. It is recommended that the governor be redesigned as an integral part of the carburetor. [Chieftain: Duck races, anyone?]
Transmission assembly: Considerable trouble was experienced with the transmission jumping out of second and third gears. Due to water operation, the mortality rate of the second gear was extremely high. It is recommended that the design be reviewed in an effort to increase gear life.
Bilge pump: Bilge pumps failed due to overheating. Investigation revealed that the overheating occurred when the bilge was free of water, which resulted in no circulation through the pump. Using organisations were instructed to open the sea cocks when the water in the bilge became too low for proper cooling of the bilge pumps. It is recommended that in TM 9-802 emphasis be placed on the necessity of allowing a certain quantity of water in the bilge. [Chieftain: Maybe I’m missing something here, but why not just turn off the pump?]
Water propeller shaft: Semi-submerged debris struck the propeller shaft and propeller which resulted in the bending of the shaft. It is recommended that a guard be designed for propeller and propeller shaft protection.
Miscellaneous: There was a requirement for adequate cargo compartment lighting when loading the vehicle during darkness. These lights should be sturdily constructed, mounted in each corner of the cargo hold flush with the top edge of the cowling and wired on an independent circuit of a separate control switch on the instrument panel.
Ambulance, ¾ ton, 4x4. Truck, carry-all, ¾ ton, 4x4. Truck, Command, ¾-ton, 4x4. Carriage, Motor, 37mm Gun M6. [Chieftain: Wait. M6? In Europe?]
Number in hands of troops.
Ambulance: 9,319 Carry-all, 389. Command, 9,574. Emergency Repair, 706. Weapons Carrier, 113,117. M6 GMC, 245.
General: The performance of these vehicles was satisfactory and reliable. They served a wide range of purposes and encountered no serious difficulty from the standpoint of design deficiency.
Seat, Attendant’s. The Chief Surgeon, ETOUSA, requested a revolving seat for the attendant so that he could observe and attend the patients during transit. A modification was developed on 30 March 1945.
Truck, ¼-ton, 4x4
Number in hands of troops: 110,082. [Chieftain: Note, this means there were more Dodge WCs than Jeeps!]
General: The service of this vehicle was excellent, considering all the abuse it was obliged to take from bad roads, high speeds, overloading, and lack of maintenance. It performed tasks that it was never intended to perform, from carrying ammunition to locations where other wheeled vehicles could not travel, to serving as a cross-country ambulance traversing roads and country considered practically impassible.
Wheel, assembly: Many wheels were sprung and twisted out of shape during tire repair. When remounted, they wobbled excessively and caused uneven and rapid tire wear. It is recommended that a wheel be developed that will make tire repair easier and still retain the qualities of the present wheel.
Absorber, Shock, Front: The shock absorbers failed on nearly all vehicles at very low mileage. It was quite evident that they were not sturdy enough to withstand the terrain and roads they encountered. Many shock absorbers were seriously bent by striking some solid object. It is recommended that a heavier, repairable double-action type shock absorber be used on future production.
Speedometer. Actual road tests made in this theater indicated that wide variations in speedometer readings existed. In the majority of cases the speedometer reading was correct for new vehicles. As mileages increased the speedometer readings became inaccurate and usually would indicate a speed faster than the actual correct speed.
- There is a distinct need for a vehicle lock, preferably on the steering wheel.
- Vacuum type windshield wipers should be made standard for all ¼-ton, x4x trucks.
- Many of the using units have indicated a desire for a winch on this vehicle. 20% winch equipment of ¼-ton 4x4 trucks should be adequate for units in the combat zone.
- Improved riding qualities through redesign of springs, shock absorbers, and seats, have been requested by all using units.
- The all-wheel-drive feature of this vehicle is not necessary for a large number of using units. Therefore it is suggested that consideration be given to designing vehicles of this size with dead front wheels.
Truck, cargo and personnel carrier, 1 1/2 –ton 6x6
Number in hands of troops: 14,009
General: The performance of this vehicle was satisfactory. Under severe operating conditions the vehicle was under-powered. Considerable trouble was experienced with transmissions jumping out of gear, especially when towing artillery. Operationally there was no serious design deficiency to cause this vehicle to be unreliable.
Pintle: Front mounted:
There was a definite requirement for a front-mounted pintle on the 1 ½-ton 6x6 cargo personnel carrier when used as the prime mover for the 57mm Gun M2, or the 105m Howitzer M3. O.T.B. #47, 10 April 45, authorized a standard front pintle mounting for carriers equipped with winch that were used by combat units.
Truck, Cargo, 2 ½-ton 6x6. (And family)
Number in hands of troops: GP, 98,633. SE, 3,634. SP, 1,071
General: The conditions these trucks operated under were seldom ideal, inasmuch as the roads were in poor state of repair, muddy, and generally difficult to negotiate. They were subject to overloading, overspeeding, and lack of maintenance for long periods of time. With this overall picture in mind, it is the opinion in this theater that the 2 ½ ton, 6x6, truck gave satisfactory and reliable performance.
Carburetor: Corrosion in the carburetors was a constant problem, due to water and dirt in the fuel. It is recommended that carburetor bowls be treated to resist corrosion when water is present.
Core, Radiator: Mineral deposits in the water of some areas caused extensive corrosion in the cooling system. Where rust inhibitors were available and used, less trouble was experienced. External corrosion was quite evident when the vehicle was subject to salt water or salt water spray. Investigation revealed that some of these radiators were made of #6 brass and others of #7 brass. The radiators constructed of #6 brass showed less corrosion.
Muffler Assembly: The tail pipe was located in such a position, that when the vehicle was operated in mud, a portion of the mud was thrown onto the exhaust muffler and the end of the tail pipe. The heat of the exhaust soon baked the mud and made it an impenetrable mass. As a result, there were many blown out mufflers and burned exhaust valves. It is recommended that the tail-pipe be relocated to afford some protection from mud entering the end.
Differential, rear axle assembly. Reports that new cargo trucks contained rear axle differentials of different ratios were received by this office. This resulted in excessive tyre wear. Differential assemblies with the same ratios were installed, and the office of Chief of Ordnance notified in a letter of 20 April 1944. It is recommended that stricter final inspection of vehicles be accomplished to prevent recurrence of this condition.
Frame: Considerable trouble was encountered with bent frames, due to overloading. The bend usually occurred directly behind the cab of the vehicle.
So that's as much as I thought it worth scanning from the Archives, apparently. The thing to bear in mind when reading the long litany of problems is that it's all relative. American equipment, as a rule, was highly durable, so the complaints are reflective of the standard that the US were used to. Other nations may well have said something like "If you're getting down to the level of complaining about mud in the exhaust pipes, or having to remove silica gel packs before starting the engine, I want to have your sorts of problems..."
It is also interesting to note how many of the problems occurred before the vehicle was delivered into the hands of the troops, occasional quality control problems, or issues at the receiving dockyard in France. Supposedly easy fixes, nothing to do with the vehicle's design, yet happened enough times to warrant mention.
Anyway, Bob will again return you to the forum thread.