m548/m1015 full tracked vehicle

Project Number 60 September 1998

M548/M1015 Full Tracked Vehicle

Northeast Forest Fire Supervisorsin Cooperation with

Michigan’s Forest Fire Experiment Station

Table of Contents

Introduction 1

General Analysis 2

Transportation of Track Unit 3

Load Considerations and Center of Gravity 3

Result of Field Trials 6Usability and Durability ....................................................................... 6Performance in Low Ground Pressure Areas............................. 6Operator Comfort Issues .................................................................... 6

REC Designs 7

Appendix A 8

Appendix B 9

Appendix C 13

Cover Photo: An M1015 with full 800 gallon water tank traversing a wet leatherleaf bog.

AcknowledgementsConsiderable help on this project came from others.

The Maine Forest Service provided the initial vehicle for REC’s use. From Maine, Bill Hamilton,Roger Stanley, Tom Parent and their staffs also made technical contributions to the project.

North Carolina Division of Forest Resources, Arkansas Forestry Commission and the Department ofDefense, Fort Polk, Louisiana, also contributed to this report.

Kirk Bradley led the REC design team. Prototype fabrication, vehicle testing and other logisticswere provided by Don Duggar, Dale Eisbrenner, Greg Tate, Pat Mattingly, John Johnston, DennisFiebelkorn, Don Pillow, Rick Greenlaw, Paul Kamprath and Vickie Sheathelm.

Inquiries, comments and suggestions regarding this project may be directedto:

Roscommon Equipment Centerc/o Forest Fire Experiment StationP.O. Box 68Roscommon, Michigan 48653-0068E-mail: [email protected]

This report is available on-line: http://www.RoscommonEquipmentCenter.com

Disclaimer

This report has been developed for the guidance of member States, Provinces, Federal Agenciesand their cooperators. The Northeast Forest Fire Supervisors assume no responsibility for theinterpretation or use of this information.

The use of trade, firm or corporation names is for the information and convenience of the user.Such use does not constitute an official evaluation, conclusion, recommendation, endorsement orapproval of any product or service to the exclusion of others which may be suitable.

mailto:[email protected]

http://www.RoscommonEquipmentCenter.com

September 1998 M548/M1015 Full Tracked Vehicle

1

IntroductionU.S. Military M548, M548A1 and M1015A1Full Tracked Vehicles are the “thin skinned”or unarmored versions of the M113 family ofvehicles.

The majority of the M113 family are armoredwith configurations that make them generallyimpractical for forest fire control use. Theunarmored versions are lighter weight andfeature a more friendly operator andpassenger cab. The unarmored versions, theiravailability through Federal Excess PersonalProperty (FEPP) and their applicability to firecontrol will be the focus of this report.

Basic chassis and layout of the M548,M548A1 and M1015 are the same. TheM548 versions are cargo carriers, rated at 6ton payload. The M1015A1 carries anelectronic warfare shelter. Only a fewhundred M1015A1s were made and some ofthe electronic equipment that they carriedhave been taken out of service. This meansthat many M1015A1s are retired and areusually in very good condition. Appendix Ashows the military data sheet and NationalStock Numbers (NSN) for these threeversions.

These vehicles will have limited use inselected locations. Applications requiring alow ground pressure unit is one situation.This report will discuss our trials in marsh andbog type environments. These units alsoperform well in rugged terrain. Although thevehicle has tracks with street pads and a roadspeed of about 33 mph, a lowboy trailer willbe needed for most transport.

The M548 was developed in 1965. In 1982,M548A1 production replaced the earliermodel. The M548A1 had improvedsuspension and cooling system. The M548shad significant cooling system problems, butmost if not all were upgraded to M548A1status at Depots. The M1015A1 wasdeveloped in 1984 and includes the upgradedsuspension and cooling system of theM548A1. The M1015, when availablethrough FEPP, will not come with the

electronics carrier, however it’s likely that thegenerator system will be part of theacquisition. This equipment can be removedto reduce weight and complexity. In all,several thousand of these “thin skinned”track vehicles were produced. Intermittentavailability through FEPP should continue fora number of years.

Several forest fire control agencies haveobtained these vehicles and successfully usedthem, especially where low ground pressurevehicles are needed. Agencies that weobtained information from include theArkansas Forestry Commission (Figure 1),Maine Forest Service (Figure 2) and the NorthCarolina Division of Forest Resources.Additionally the U.S. Army at Fort Polk,Louisiana, produced a design and report titled,Fire Track. For this project they used anM548A1 vehicle with 1,000 gallon watertank. Compressed Air Foam, front blade anda fireline plow were included on the Fort Polkversion. Information has been available asthe “Fire Track” vehicle fromDPW/ENRMD/NRMB, 1843 23rd Street, FortPolk, Louisiana 71459.

Figure 1 - An M548 fitted with a military 500gallon fuel cell and compressed air foamsystem (CAFS). Completed by ArkansasForestry Commission.

For this report REC tested and designedequipment for a vehicle provided by the Stateof Maine as well as one from the Michigan

M548/M1015 Full Tracked Vehicle REC #60

2

Department of Natural Resources. The designincludes three separate components:

• A bumper and limb rising system toprotect the windshield and cab whenworking off road and in forestedenvironments.

• An 800 gallon tank.• A hard top cab. These units normally

come with canvas cabs. The military alsohas a fiberglass cab with a gun turretopening. The fiberglass cabs are usuallydifficult to get.

The remainder of the report will use the term“M548” to mean any of the M548 or M1015models.

Figure 2 - Windshield and cab protection onan M1015 unit produced by Maine ForestService. The cab was a military compositematerial type with gun turret opening.

General AnalysisThe Maine Forest Service loaned an M1015to make an assessment of its’ utility forforest fire control. Before obtaining any pieceof equipment, an agency should determineits’ usefulness. For a specialized piece ofequipment like the M548 series this isextremely important. The M548 equipment isnot for everyone. It is large which affects

how it can be transported. It will requirespecial maintenance and should be operatedby skilled personnel. The remaining sectionswill discuss various characteristics of thevehicle that will help agencies make adecision as to whether acquisition is properfor them.


3

Transportation of the Track UnitThe M548 has rubber pads on the track and atop speed of approximately 33 mph. Thismakes it possible to drive the vehicle at lowto moderate speeds on hard surfaces withoutdamaging pavement. There are obviouslysafety concerns about transporting thevehicle this way and it is expected that travelon improved roads would be limited. Thevehicle does have the flexibility to move todifferent parts of the fire site without specialtransportation requirements. It also can crosspaved roads without special provisions.

It is likely that an agency will transport theunit to a fire site with a semi and low-boytrailer. The need for a special transport unitmakes the M548 an unlikely choice for localfire department use. As shown in theAppendix A, the vehicle is 105.75 incheswide. This is a “wide load” under normaltransporting circumstances. The width of thevehicle is just under 103 inches if the twofront track guard step plates are removed(Figure 3). Each plate is held by four bolts.Removal of these plates either temporarily or

permanently reduces the vehicle’s widthenough to be transported as a normal load onmajor highways.

Figure 3 - Removing the track guard stepplates (shown installed near photo’s center)reduces the overall vehicle width to under103 inches. This eliminates the need forwide load permits.

Load Considerations and Center of GravityAs we do with any military-obtained vehicle,REC stripped the M548 unit of items that wedid not need. This included seats and thefloor boards in the cargo unit and the auxiliarygenerator of the M1015. When this is done,the vehicle weighs approximately 14,300 lbs.This is about 2,000 lbs. less than the netweight for an M548 cargo carrier. Themilitary designates 28,400 lbs. as the combatweight for the unit. Hence there is more thansufficient payload available for conversion towildland fire fighting use.

Because the M548 has a large payloadcapacity, the limiting factor on how muchload you carry will probably have more to dowith your use. Much of the interest in usinga tracked rather than wheeled vehicles has todo with the decreased ground pressure. Thelarger surface area of the tracks helps support

the vehicle above the ground in a marsh, bogor other low area. On paper the M548actually has a high ground pressure for atracked vehicle. At its’ full combat weight,the ground pressure is listed at 8.6 psi. Thisis considerably more than even crawler dozerswith standard width pads. However, theM548 does have a track system thatgradually tapers up to the drive sprocket. Asthe vehicle sinks below the surface, it gainsmore track surface area. This reduces theground pressure until the vehicle reaches thelevel of the upper (drive) sprocket. For therest of this report we will refer to this as the“secondary” ground pressure. We will definethe “initial” ground pressure as thatcalculated using the surface area of the padthat would contact the ground when theM548 sits on hard ground. In other words,


4

when the unit has not “sunk” down belowthe surface level.

Figure 4 is an estimate of the groundpressure, both initial and secondary forvarious payloads added to the M548 strippedweight. Figure 5 is an estimate of the groundpressures for various water tank capacities.Keep in mind that this is only an estimate to

help you plan a unit. The actual groundpressure will depend on the tank materialweight and other items that you add. For acomparison, standard track, crawler dozersnormally have a ground pressure of 6 to 7.5psi. Low ground pressure or wide padcrawler tractors will typically exhibit groundpressures of 4 to 4.75 psi.

Ground Pressure vs Various Payloads

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

050

010

0015

0020

0025

0030

0035

0040

0045

0050

0055

0060

0065

0070

0075

0080

0085

0090

0095

00

1000

0

1050

0

1100

0

1150

0

1200

0

1250

0

1300

0

1350

0

Payload (lbs)

Gro

un

d P

ress

ure

(p

si)

Initial Ground Pressure

Secondary Ground Pressure

Figure 4 – Ground Pressure vs Various Payloads

The REC designed water tank for the M548 isabout 800 gallons. We felt this would givethe users some flexibility. Most users wantedlarge capacity available for use in areas wherethe soil structure was capable of handling thehigher ground pressure. It was assumed thatif lower ground pressure was required thatthe load could be reduced by hauling lesswater. The M548 vehicle is a good candidate

for doing this. It has a low center of gravity,very wide stance and the weight of the wateris a fairly small compared to that of thevehicle. Hence, there is little or no affectfrom water shifting in a half empty, baffledtank. Additionally, M548 does not operateon public highways at normal highwayspeeds, thus the vehicle can operate withpartial water loads in a safe manner.


5

Estimated Ground Pressure for Various Tank Capacities

0

1

2

3

4

5

6

7

830

0

400

500

600

700

800

900

1000

Tank Capacity (US Gallons)

Gro

un

d P

ress

ure

(p

si)

Initial Ground Pressure

Secondary Ground Pressure

Figure 5 – Estimated Ground Pressure for Various Tank Capacities

As always, remember to consider other loadsthat will be placed on the vehicle. Forexample, REC’s hard cab design for this unitweighs 320 lbs. The heavy duty bumper andlimb riser set adds another 600 lbs. Estimatethe occupants weight at 200 lbs. each, thenadd in the weight for other items you plan tostore or carry on the vehicle.

The vehicle’s performance will also beaffected by its’ fore to aft balance. Figure 6shows the center gravity location for the astripped M548. It is about 2 feet in front ofthe center bogie wheel. Ideally you wouldlike to operate with the vehicle’s weightcentered directly above or slightly behind thecenter bogie. Because of the engine and cabweight, it is obvious that a large load in therear would be necessary to shift the center ofgravity to the center. Figure 7 shows theapproximate center of gravity point of REC’s800 gallon tank when full and empty. Thetank design is discussed later in the report.

Figure 6 – Center of gravity location of“stripped out” M548.

Figure 7 – M548 center of gravity locationwith REC 800 gallon tank.


6

Engine RPM Decibels

700 911000 961500 1002000 1072500 108Full Speed 109

Figure 8. Measured sound levels insideM548 cab while driving on pavement.

Result of Field TrialsREC spent a considerable amount of timeusing and testing the M548. We have brokenour observations into three areas. First is“usability and durability.” The second,“performance and low ground pressuresituations.” The third is “operator comfortissues.”

Usability and Durability – At first look, theM548 is big and it is especially wide. Despitethis, it gets around off highway fairly well.The track system makes it maneuverable.The unit is generally durable, especially whenfitted with a heavy duty bumper and somelimb risers as illustrated in the REC drawings.The underbelly has no vulnerable parts.Lastly, the M548 has plenty of power. TheDetroit Diesel 6 cylinder, 212 hp engineprovides more than enough to move theM548 with a heavy payload. The unit canpush over smaller trees and has plenty ofground clearance to climb over them. Theunusual width does make traveling two-trackroads a little more difficult. All in all, itperforms well off the road.

The U.S. Army sets the maximum speed at33 mph. We had no trouble reaching thatspeed on pavement. The rubber street padsprevented damage to the asphalt and providethe ability for the vehicle to cross highwayswithout taking special precautions.

The unit handles slopes well. Its’ center ofgravity is relatively low compared to its’ widetrack. This makes it a relatively safe vehiclein steeper terrain.

Performance in Low Ground Pressure Areas –As mentioned previously, the ground pressurefor this vehicle is relatively high for a trackedvehicle. We were surprised on how well ittraversed low boggy areas. The M548 willsink somewhat in soft soil and marshes. Thiswill especially be true if it carries a full waterload. However, the vehicle has three thingsgoing for it. First, as mentioned previously, itgains more track surface as it sinks.Secondly, the flat belly pan that makes up theunit’s bottom, will prevent it from sinking any

further. When it sinks to the belly pan, theground pressure gets really low. Third, theengine has plenty of power. We found thatthe engine had no problems skidding the uniton its’ belly pan, across leatherleaf bogs.With leatherleaf and similar such areas, thereis generally plenty of root structure. If thestructure is there, the tracks will get enoughtraction. If there is enough traction, wefound that there is enough power for the unitto skid itself along. The caution is using it inareas that require low ground pressure buthave little root structure and no bottom.Cattail marshes would be an example. Inthese cases, you will get stuck.

Operator Comfort Issues – The high noiselevel produced by its’ power plant is anothercharacteristic of the M548. We measuredsound levels of 109 decibels while travelingthe top speed of 33 mph on a paved road.Much of the noise comes from the fact thatthe occupants sit right over the diesel engine.Only a thin layer of sheet metal separates theengine from the occupant compartment.Secondly, it can pick up a fair amount of roadnoise at that speed. Hearing protection is anobvious necessity. Communications betweenoccupants in the cab was difficult at highengine rpms.

REC put sound insulation on the inside backof the cab under the seats and floor boards.By doing this we were able to reduce thesound level by nearly 10 decibels. Becausesound is measured a logarithmic scale, 10decibels is a very significant decrease. But100 decibels is still very loud and requires


7

hearing protection if in that environment verylong. Figure 8 shows the soundmeasurements taken at ear level of theoperator inside an enclosed uninsulated M548cab. The measurements were taken atvarious engine speeds while operating thevehicle on pavement.

The seats in the M548 are not comfortable.There is a bench seat for the passengers.The seat portion of the bench hinges open forengine service access. Because of the needfor engine access, adding more comfortableseats would be a challenge. We did add a

molded off-road race vehicle seat for thedriver. We also added a four-point seat beltharness for the driver to reduce the amountof fatigue from being jostled during operation.A grab handle was put on the inside of bothdoorways to help occupants get in and out ofthe cab easier.

Noise is the biggest comfort and safety issuethat we found. Surprisingly the operatorslook past the noise issue and were impressedwith the vehicle’s ability to handle difficultoff-road situations.

REC DesignsREC has created designs to modify the M548for wildfire control. These designs fit fivedifferent categories.

• A steel cab to replace the canvas cab thattypically comes with these units.

• A heavy duty bumper and limb risersystem to help protect the front of thevehicle and its’ windshield and cab.

• A 12-volt electrical system for runningadd on accessories. The 12-volt systemis in addition to the vehicle’s 24-voltsystem.

• An 800 gallon water tank that slips intothe cargo area of the vehicle and is heldin by four turnbuckles.

• Various accessories to help complementthe vehicle’s use. This includedinstallation of the REC low-cost turret,steps for better access and side mountedhose reels.

Because the M548 will have limited use forfire agencies, this report includes only theoverall drawings for the five design categorieslisted above. The drawings are meant to givea general idea about what we did. If you likewhat you see, please contact us and we willprovide you with a packet of drawing details.Packets available are listed below.

M548 Design Packets Packet NumberM548 Cab Design #60AM548 Bumper and Limb Risers #60B12V Alternator System #60C800 Gallon Water Tank and Mounting for M548 #60DOther M548 Accessories #60E


8

Appendix A

The following is data about U.S. Military M548A1 vehicles from the U.S. Army Tank AutomotiveCommand, March 1993.

Description Specification Unit of Measure

Weight, Combat 28,400 PoundsWeight, Net 16,390 PoundsLength 226.5 InchesWidth 105.75 InchesHeight 105.5 InchesHeight, Min Reducible 76 InchesAcceleration (0-20 MPH) 14 SecondsAcceleration (0-30 MPH) 56 SecondsMaximum Speed 33 Miles per HourRange 285 MilesGround Pressure 8.62 PSIWidth of Trench Crossing 66 InchesVertical Obstacle Crossing 24 Inches

Slope Capability 60 PercentSide Slope Capability 30 PercentFuel Capacity 105 GallonsOperator 1Passengers 3Engine Detroit Diesel, 212 BHP, 6V53

Transmission Allison TX-100-1, 3 Speed,Automatic

Controlled Differential Single Speed, DS-200Amphibious No

National Stock Numbers (NSN)

M548 2350-00-078-4545M548A1 2350-01-096-9356

M1015A1 2350-01-136-8745


9

Appendix B

Figure B-1 - Front view of an M1015 modified by REC. Limb risers and bumper were part of themodification.

Figure B-2 – The 800 gallon REC tank with pump and foam proportioner. The tank sets in fourcradles (not visible). Enclosed storage is located below the pump apron, accessed by opening thelower tailgate.


10

Figure B-3 - The tank is held in the cradles by four turnbuckles. The right rear turnbuckle is shownin the center of the photo. It is attached to the tank and to a cargo tiedown ring in the M548.

Figure B-4 - A 12-volt alternator and its' mounting bracket were mounted to the existing 24-voltalternator. This provided power to the fire related accessories. Drawings are provided (AppendixC).


11

Figure B-5 - View inside of the REC cab. A 1x1 inch square tube framework supports the 11 gaugesteel skin. The rear windows were a clear polycarbonate.

Figure B-6 - In one design version, REC cut out booster hose openings through the side walls(Design Packet #60E). Note the water tank overflow and vent tube outlet (upper right). This was aconcept borrowed from Maine Forest Service.


12

Figure B-7 - The REC low cost turret was integrated into the front of the M548 (see REC Project#58). The turret provides water delivery when it is not practical to use booster lines.

Figure B-8 - Fold down steps were put at each rear corner to reduce the step up distance to thecargo area (Design Packet #60E).


13

Appendix C

REC M548 Component Designs

The online version does not include Appendix C drawings directly. Some M548 ComponentDrawings may be available online as individual files. Look at the “Online Reports” page of the RECweb site for current listings.

m548/m1015 full tracked vehicle

Documents