Caterpillarasphalt paverasphalt screed

Caterpillar AS3251C

Maintenance schedule, common problems & OEM parts breakdown

The Cat AS3251C is an Extend-A-Mat asphalt screed, not a self-propelled paver. It has no engine, no drivetrain, and no undercarriage of its own — it bolts to a Cat track or wheel paver tractor and draws hydraulic power for its extenders and vibrator plus electric current for its heated plates from that host machine. Base screed width runs around 2.4 m (8 ft) with rear-mounted hydraulic power-extending arms that carry paving width out to roughly 4.7 m (15 ft 5 in), down to a minimum of about 1.8 m (6 ft) for narrow work. It rides in Cat's C-series Extend-A-Mat lineup alongside siblings such as the AS2252C, AS2302C, AS3301C, AS4251C, and AS4252C, which differ mainly in base width and maximum extension. Screed plates are abrasion-resistant alloy steel, the vibrator runs up to roughly 3,000 vpm, and the unit mounted to period Cat wheel and track paver tractors such as the AP555E and AP655 class of machines.

The C-generation Extend-A-Mat screeds added an electronic screed controller for automated crown and slope adjustment and refined the electric heat circuit compared with earlier Extend-A-Mat generations, but Cat has not published a documented one-for-one successor line carrying the AS3251C name forward. Current Cat paver platforms such as the AP600, AP1000, and AP1055 class ship factory-fit with the newer SE-series screeds instead. That shift means the AS3251C now lives mainly in the used and parts market as a rebuild-or-replace candidate for shops still running older AP-series tractors: demand centers on screed plate resurfacing or replacement, extender slide-tube and bushing rebuild kits, vibrator bearing replacement, and heat-element and wiring harness replacement rather than new-unit sales.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Caterpillar AS3251C specifications

Engine

Identity	AS3251C is an Extend-A-Mat asphalt screed attachment, not a self-propelled paver. It has no engine, drivetrain, or travel speed of its own; it mounts on the rear of a separate Cat paver tractor (documented on AP555E and AP655 tractors) and draws hydraulic and electric power from that host machine.
Power source	Hydraulic and electric power supplied by the host paver tractor. No onboard engine, fuel system, or emissions rating applies to the screed itself.
Heating system	Electric heat control panel with three temperature settings for screed plate heating, automatically regulated to the selected setting. Screed family also offers an LPG heating option depending on configuration; confirm actual heat source on the specific unit.

Weights

Screed-only weight	Not separately published in available factory literature. Weight is only documented as part of a paver-plus-screed combination.
Combined operating weight (host tractor + AS3251C)	Approx. 16,250 kg (35,810 lb) as documented for an AP555E tractor fitted with the AS3251C screed. This figure is for the paver-and-screed combination, not the screed alone, and will vary by host tractor model.
Comparison figure	Same AP555E tractor with an AS2252C screed instead is documented at approx. 16,010 kg (35,290 lb), illustrating how screed choice shifts combined operating weight by roughly 230-500 kg (500-1,100 lb).

Dimensions

Paving width range (documented variants)	Sources vary slightly by configuration: one factory figure gives minimum 1.8 m (6'0"), standard range 2.4-4.7 m (8'0"-15'6"), maximum 6.1 m (20'2"); another factory figure states an overall paving range of 2.44-6.15 m (8'0"-20'2"). Treat 2.4 m as the practical minimum working width and 6.1-6.15 m as the maximum extended width; exact minimum varies by extension package and configuration.
Screed/extender plate size	Main and extender screed plates approx. 457 mm (18 in) front-to-back.
Screed plate thickness	Approx. 12.7 mm (0.5 in), abrasion-resistant Hardox 400 material.
Maximum paving depth	Approx. 305 mm (12 in).
Combined machine length (host tractor + AS3251C)	Approx. 6.1 m (20'0") overall length documented for a host tractor fitted with this screed; varies by host tractor model.

Performance

Travel speed	Not applicable. The screed has no propulsion of its own; travel and paving speed are functions of the host paver tractor, not the screed.
Vibration system	Hydraulically driven vibrators on the main screed and extenders, synchronized for matching frequency and amplitude, maximum vibrator frequency approx. 3,000 RPM.
Tamper system	Electrically controlled tamper adjustment, designed to prevent marks on the finished mat surface.
Crown control	Power crown control adjustment; specific crown-angle figures not published for this exact model.

Service capacities (summary)

Fuel tank	Not applicable. The screed has no engine or independent fuel system.
Hydraulic system	No separate hydraulic reservoir; screed vibrators, extenders, and tamper run off the host paver tractor's hydraulic system.
Engine oil	Not applicable.
Cooling system	Not applicable.

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

AS3251C fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase	Not applicable	The AS3251C is an Extend-A-Mat asphalt screed attachment, not a self-propelled machine. It has no engine of its own; power and hydraulic flow come from the host paver tractor.
Cooling system	Not applicable	No engine, so no coolant system on the screed itself.
Fuel tank	Not applicable	No fuel tank on the screed; fuel is carried and supplied by the host tractor only.
Hydraulic system (screed circuit)	Not separately documented for this unit	The screed's extender, vibrator, and slope functions run off the host paver tractor's hydraulic system and tank. There is no standalone screed hydraulic tank or independent fill spec; hydraulic fluid type and capacity follow the host tractor's OMM (matched to the tractor model the AS3251C is mounted on, e.g. AP-family pavers).
Final drives / axles	Not applicable	The screed has no final drives or axle/differential compartments; it is a towed/carried attachment, not a driven unit.
Grease points (screed frame, extender slides, vibrator bearings, end gate pivots)	Spec only, no fill volume documented	Multipurpose or moly-fortified Caterpillar chassis grease is used at the screed's pivot, slide, and bearing fittings, consistent with Caterpillar's general grease line for extreme-pressure, high-load points; exact grease points and intervals are set by the screed OMM/lube chart, which was not located as a standalone public document for this model.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar AS3251C maintenance schedule

Service interval	Tasks
Every 50 h	Inspect screed plates for wear, gouges, or uneven wear pattern across the full working width Grease extender slide tube and pivot points at all fittings Cycle the electric heat circuit before startup and confirm even plate temperature with no cold spots Listen and feel for unusual vibrator noise, chatter, or excess play at the vibrator housing Check hydraulic quick-disconnect couplers between the host tractor and screed for leaks or damage Clear debris from crown and slope sensor mounts and cabling
Every 250 h	Grease extender slide rails, gib strips, and leveling arm pivots thoroughly Check vibrator bearing housings for play, heat, or abnormal noise under load Measure screed plate thickness against minimum wear spec and log the reading Inspect heat element wiring, connectors, and the control relay or contactor for corrosion or chafing Check tow point and leveling arm pins and bushings for wear Re-torque main frame and extender mounting fasteners
Every 500 h	Check extender slide tube and gib/wear-strip clearance and adjust as needed Inspect and re-torque the crown adjustment linkage Calibrate crown and slope sensors and the screed grade-control controller against a known reference Thermal-check heat elements for hot or cold spots and replace any that are failing Inspect flow-gate or auger linkage (if fitted) for wear at pins and bushings Inspect main screed-to-extender overlap and seal strips for wear
Every 1,000 h	Remove and inspect vibrator bearings for wear or pitting, replace if play exceeds tolerance Check screed plate flatness and twist across the full width and correct as needed Service extender slide tube bushings and replace any that are worn Verify screed controller calibration is current and inspect the wiring harness for chafing Inspect the frame for cracks at extender mounting brackets and tow points Check leveling arm and depth-control linkage for wear
Every 2,000 h	Evaluate screed plates for resurfacing or replacement across the full working width Rebuild the extender slide tube assembly, including bushings, wear strips, and seals Replace vibrator bearings as a set regardless of measured play Pressure-check hydraulic hoses and quick-disconnect couplers feeding the screed cylinders Check main frame squareness and extender alignment against factory tolerance Inspect the heat element harness and junction box for insulation breakdown
Every 4,000 h	Tear down extender assemblies and replace all slide bushings, wear strips, and seals Resurface or replace screed plates across the full working width Replace vibrator shaft and bearing assemblies and inspect eccentric weights Rebuild main frame pivot points and tow-arm bushings and re-check frame squareness Replace heat element sets and rewire the heat circuit harness as needed Fully recalibrate the grade and slope control system after rebuild work

Servicing the AS3251C beyond the schedule

Predictive Maintenance & Fluid Analysis

The AS3251C has no fluid reservoir of its own — its extender and vibrator circuits run off the host tractor's hydraulic system, so sample and trend that tractor's hydraulic fluid condition rather than testing the screed separately. Track screed plate thickness readings over time to project replacement timing, log vibrator bearing noise and heat trends at each interval, and watch heat-element amperage draw for early signs of element or wiring failure before a cold spot shows up in the mat.

Corrective & Common Repairs

Uneven mat edges or transition marks usually trace back to worn extender slide-tube bushings or gib strips, not the plates themselves — check alignment before condemning a plate. Cold or hot spots in the mat point to a failed heat element, bad connector, or a tripped contactor in the heat circuit. Vibrator chatter or noise calls for bearing inspection and replacement. Leaks at the tractor-to-screed hydraulic quick-disconnect couplers are a common source of lost extender response.

Overhaul & Rebuild Points

Major rebuild work on the AS3251C centers on the screed plates, the extender slide tubes, and the main frame. Worn plates get resurfaced or replaced across the full working width rather than patched. Extender slide tubes need bushings, wear strips, and seals rebuilt as a set once clearance opens up. Check main frame and extender-bracket squareness after any heavy rebuild — a twisted frame will re-introduce mat defects even with new plates and bushings installed.

Seasonal & Environment Servicing

Confirm the electric heat circuit brings plates to working temperature evenly before cold-weather paving starts — a weak element that passes a summer check can fail to reach temperature in cold ambient air. Protect heat-element wiring, connectors, and the control box from moisture intrusion and corrosion during wash-downs and wet storage. When the screed sits idle, block and support the extenders rather than leaving them hanging on the hydraulic circuit, which prevents frame sag and hose strain over time.

AS3251C attachments & work tools

Identity: screed attachment, not a standalone paver

The AS3251C is an Extend-A-Mat vibratory screed, part of Cat's AS-series family, not a self-propelled paver. It mounts to and is towed/pushed by a separate wheeled or tracked paver tractor; it has no engine or undercarriage of its own.

Host tractors

The AS3251C pairs with Cat's large paver tractors in this class, including the AP600, AP655, AP1000 and AP1055 lines from the generation preceding the 2022 F-series refresh. Later F-series tractors shifted to the newer SE-series screed lineup, so AS3251C compatibility centers on the pre-refresh tractor generation.

Paving width range and extensions

Standard hydraulic paving range runs about 2.4-4.7 m (8'0"-15'6"), with bolt-on extensions taking maximum width to about 6.1 m (20'2"); minimum width is about 1.8 m (6'0"). Exact figures vary by configuration and extension kit fitted.

Screed plates and nose bar

Main and extender screed plates measure 457 mm (18 in) front-to-back and are built from abrasion-resistant alloy steel for wear life. A curved nose bar design gives precompaction and improves material flow under the screed.

Extender mounting and structure

Extenders are rear-mounted and hydraulically driven for width changes on the move. A triangular support arrangement with two extendable support tubes plus a third frame member gives torsional rigidity and keeps the extenders from flexing under load.

Vibration and tamper system

Hydraulically driven vibrators on the extenders are synchronized in frequency and amplitude with the main screed for consistent density across the full mat width. Tamper-bar variants exist in this screed family in addition to vibratory-only setups; confirm the specific configuration on the unit's data plate.

Auger adjustment

The auger assembly is hydraulically adjustable, with roughly 215 mm (8.5 in) of vertical travel to manage material head feeding the screed as paving width changes.

Heating system options

Screed heat is available as an electric system, drawing on a tractor-mounted generator rated around 25 kW at 60-100 Hz for both screed heat and an auxiliary power panel, giving warm-up in about 30 minutes or less. A diesel fuel burner heating option is also used on this screed family, with burner lines fitted with a quick-disconnect coupling so the same lines can switch to a wash-down function.

Cooling system

An electronically controlled, hydraulically driven variable-speed fan provides on-demand cooling, reducing engine power draw, sound level, and fuel use compared to a fixed-speed fan.

Controls and diagnostics interface

A CANbus electrical system on the screed interfaces with the Advisor display on the host tractor, giving the operator simplified screed diagnostics from the tractor console.

Related screed family members

The AS3251C sits alongside sibling C-series Extend-A-Mat screeds (AS2252C, AS2302C, AS3301C, AS4251C, AS4252C) that share the same design family but differ in base width and maximum extended paving width; do not carry width/weight figures across these siblings without confirming the exact model.

All AS3251C assemblies by section

Every catalogued assembly group for the Caterpillar AS3251C. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Controls

102-2703 Adjuster Gp-Height -Manual

10***03	Adjuster Group-Height; -Manual	1
10***47	Gear-Worm	1
10***50	Guide-Bushing	1
11***81	Worm	1

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276-4579 Adjuster Gp-Height

10***03	Adjuster Group-Height; -Manual	2
10***04	Bolt-Shoulder	2
10***24	Tube As; (Vertical)	4
10***33	Clevis	2

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197-9844 Chain Gp-Screed

10***87	Link-Connecting	1
13***39	Chain	71
19***33	Link-Offset	1
19***44	Chain Group-Screed	1

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287-0326 Control Gp-Thickness -Lh Thread

27***84	Film-Instruction; (Mat Thickness, Cw To Increase)	2
28***26	Control Group-Thickness; -Lh Thread	1
28***26	Shaft As	2
30***73	Trunnion	2

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287-0327 Control Gp-Thickness -Rh Thread

27***83	Film-Instruction; (Mat Thickness, Ccw To Increase)	2
28***27	Control Group-Thickness; -Rh Thread	1
28***24	Shaft As	2
30***74	Trunnion	2

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277-9935 Control Gp-Thickness -Rh Thread

27***83	Film-Instruction; (Mat Thickness, Ccw To Increase)	2
27***35	Control Group-Thickness; -Rh Thread	1
28***94	Shaft As	2
30***72	Trunnion	2

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277-9934 Control Gp-Thickness -Lh Thread

27***84	Film-Instruction; (Mat Thickness, Cw To Increase)	2
27***34	Control Group-Thickness; -Lh Thread	1
28***90	Shaft As	2
29***65	Trunnion	2

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276-4590 Crown Gp-Power

10***01	.. Roller, Bearing	2
10***38	Pointer	1
10***39	Key-Square	1
19***44	Chain Group-Screed	1

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102-2699 Jack Gp-Sloper

10***99	Jack Group-Sloper	1
10***46	Gear-Worm	1
10***49	Guide-Bushing	1
10***64	Bearing-Thrust	2

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277-2005 Motor Gp-Power Adjuster

07***77	Bushing-Terminal	2
10***02	Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness)	1
10***87	Sleeve; (26-cm)	0
12***07	Screw-Hex; (10-16x1-In)	8

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277-2004 Motor Gp-Power Adjuster

07***77	Bushing-Terminal	2
10***02	Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness)	1
10***87	Sleeve; (26-cm)	0
12***07	Screw-Hex; (10-16x1-In)	8

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277-2006 Motor Gp-Power Adjuster

07***77	Bushing-Terminal	2
10***02	Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness)	1
10***87	Sleeve; (26-cm)	0
12***07	Screw-Hex; (10-16x1-In)	8

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112-1276 Shaft Gp-Drive -Eccentric Weight

02***87	Fitting-Grease; (Universal Joint)	1
11***76	Shaft Group-Drive; -Eccentric Weight	1
24***28	Seal	1
24***41	Kit-Bearing; (Drive Shaft)	2

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282-7961 Shaft Gp-Drive -Non-Actuated

17***69	Kit-Bearing; (Universal Joint)	1
19***11	Shaft As	1
28***61	Shaft Group-Drive; -Non-Actuated	1
28***63	Spindle As	1

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276-4573 Sloper Gp-Power

06***93	Lockwasher-Bearing	2
10***99	Jack Group-Sloper	2
10***00	. Axle, Rod End	2
10***39	Key-Square	2

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Electrical And Starting System

351-5775 Electronics Gp-Implement

10***06	Receptacle Kit; (Includes Wedge And Receptacle Assem.)	1
12***74	Tube-Heat Shrink; (5.72-mm Dia)(950-cm)	0
12***75	Tube-Heat Shrink; (7.44-mm Dia)(560-cm)	0
24***12	Switch As-Toggle; (Right Extender Width Sw)	3

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322-9152 Sensor Gp-Temperature

09***66	Washer; (Hard) (4.5x9x1mm Thk)	24
10***02	Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness)	1
13***00	Clip; (Tab)	10
13***89	Clip; (Ladder)	2

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334-7882 Sensor Gp-Temperature

09***66	Washer; (Hard) (4.5x9x1mm Thk)	12
25***11	Relay As; (24-Volt)(Screed Control)	4
27***12	Plate As	1
27***16	Harness As-Panel	1

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296-1288 Software Gp-Implement

03***39	Ring-Back-Up	1
12***75	Ring-Wear	2
13***19	Kit-Seal; (Extender Cylinder)	1
16***92	Ring-Wear	2

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276-4607 Wiring Gp-Heater

10***03	Plate-Cover	1
10***05	Plate	3
11***60	Strap	1
13***41	Adapter-90 Degree	1

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306-7603 Wiring Gp-Panel

30***03	Wiring Group-Panel	1
31***08	Kit-Seal	1

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276-4606 Wiring Gp-Screed

09***99	Fitting-Grease; (Hydraulic)	2
10***35	Key-Square; (3/16in X 3/4in Lg)	2
10***33	Key-Square; (1/4in X 3/4in Lg)	4
11***76	Shaft Group-Drive; -Eccentric Weight	1

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276-4552 Wiring Gp-Screed -Extension

25***57	Kit-Seal; (Check Valve)	1
25***37	Valve Group-Solenoid; (24-Volt)	1
27***10	Coil-Solenoid	2
27***52	Wiring Group-Screed; -Screed Extension	1

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Electrical System

289-3576 Box Gp-Screed Control -Lh

10***03	Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge)	1
11***62	Tube-Heat Shrink; (10.85-mm Dia)(299-cm)	0
13***01	Clip	1
15***60	Kit-Connecting Plug; (3-Pin)(Engine Sensor Wiring Harness)	1

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348-7769 Box Gp-Screed Control

10***05	Plate	4
15***83	Clamp-Half	8
17***15	Strap; (Dual Clamp)	3
1G***59	Clamp	4

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289-3575 Box Gp-Screed Control -Rh

10***03	Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge)	1
11***69	Lamp; (24-Volt)	0
11***62	Tube-Heat Shrink; (10.85-mm Dia)(299-cm)	0
13***01	Clip	2

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Frame And Body

276-4589 Arm Gp-Drop

10***82	Shoe As-Cutoff; (1 Foot)	1
10***88	Shoe As-Cutoff; (2 Foot)	1
27***89	Arm Group-Drop	1
6V***87	Locknut; (M12x1.75-Thd)	2

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276-4582 Deflector Gp

10***14	Handle	1
16***89	Tack-Fastener	4
18***68	Plate-Serial Number	1
24***41	Padlock Group; (1 On Fuel Tank Cap) (1 On Hydraulic Tank Cap) (1 On Grill Latch)	3

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276-4604 Frame Gp-Screed

27***04

Frame Group-Screed

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276-4603 Gate Gp-End

27***03

Gate Group-End

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276-4605 Plate & Heater Gp-Screed -Electric Heat

27***05

Plate & Heater Group-Screed; -Electric Heat

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308-3130 Plate Gp-Screed -Electric Heat, Main

30***30

Plate Group-Screed; -Electric Heat, Main

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308-3132 Plate Gp-Screed -Electric Heat, Extender, Lh

30***32

Plate Group-Screed; -Electric Heat, Extender, Lh

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308-3131 Plate Gp-Screed -Electric Heat, Extender, Rh

30***31

Plate Group-Screed; -Electric Heat, Extender, Rh

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Hydraulic System

135-0218 Cylinder Gp-Hydraulic -Extender

10***31	Nut-Spring	6
10***83	Screw-Flat Head; (1/2-13x1-In)	10
11***50	Clamp As; (Bar)	2
13***18	Cylinder Group-Hydraulic; -Extender	1

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276-4585 Lines Gp-Extension

10***19	Locknut; (2-1/4-16-Thd)	2
10***47	Washer	2
24***16	Actuator Group	4
25***36	Support As; (Rh)	4

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276-4584 Lines Gp-Vibratory

12***64	Receptacle As-Connector; (1-Pin)	2
25***37	Bracket; (Rh)	16
25***01	Plate-Main	1
27***84	Lines Group-Vibratory	1

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308-2125 Motor Gp-Gear

12***64	Receptacle As-Connector; (1-Pin)	2
25***37	Bracket; (Rh)	8
25***06	Plate; (Extender, Rh)	1
30***42	Heater As-Screed; (240-Volt, 1099-Watt)	1

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300-0504 Valve Gp-Solenoid -Extender, Slope

12***64	Receptacle As-Connector; (1-Pin)	2
25***37	Bracket; (Rh)	8
25***13	Plate; (Lh Extender)	1
30***04	Valve Group-Solenoid; -Extender, Slope	1

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276-4572 Vibratory Gp

14***25	Plate As	2
27***72	Vibratory Group	1
6V***87	Locknut; (M12x1.75-Thd)	8
8T***83	Bolt (M12x1.75x40mm); (M12x1.75x40-mm)	8

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Implements

283-5613 Plate Gp-Bevel End

28***13

Plate Group-Bevel End

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283-5616 Plate Gp-Bevel End

28***16

Plate Group-Bevel End

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283-5615 Plate Gp-Bevel End

28***15

Plate Group-Bevel End

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283-5614 Plate Gp-Bevel End

28***14

Plate Group-Bevel End

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283-5617 Shoe Gp-Cutoff

28***17

Shoe Group-Cutoff

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Machine Arrangement

276-4539 Screed Ar -As3251c, U.S.

27***39	Screed Ar; -As3251c, U.S.	1
27***72	Vibratory Group	1
27***73	Sloper Group-Power	1
27***79	Adjuster Group-Height	1

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Operator Station

276-4588 Platform Gp-Operator

14***28	Plate As	2
27***88	Platform Group-Operator	1
6V***87	Locknut; (M12x1.75-Thd)	8
8T***83	Bolt (M12x1.75x40mm); (M12x1.75x40-mm)	8

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Service Equipment And Supplies

276-4609 Plate & Film Gp

27***09

Plate & Film Group

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AS3251C serial number reference

The PIN plate for the AS3251C sits on the screed main frame near the tow-point/hitch end where it couples to the paver tractor, not on a separate engine since the screed carries none. Read the first 3 characters as the prefix (identifies this specific screed model and its production run) and the following digits as the sequential unit number within that run.

Prefix	Identifies	Notes
JJN	AS3251C Extend-A-Mat screed, base/only documented run	Serial prefix JJN00001-UP is tied specifically to the AS3251C screed in factory parts-catalog listings. No engine of its own — it is a trailing attachment powered and controlled from the host paver tractor via hydraulics, electrics, and the CANbus/Advisor interface, so no engine fitment applies. Plant/region and exact production years are not documented in available sources — confirm with dealer.

Frequently asked questions

Does the Caterpillar AS3251C have its own engine?

No. The AS3251C is an Extend-A-Mat screed attachment, not a self-propelled machine. It has no engine, fuel system, or drivetrain of its own — it mounts to a Cat paver tractor and draws hydraulic power for its extenders and vibrator, plus electric current for its heated screed plates, from that host machine.

What is the operating weight of the AS3251C?

A screed-only weight isn't published separately in factory literature. What is documented is a combined tractor-plus-screed operating weight: an AP555E paver fitted with the AS3251C screed lists a combined operating weight of roughly 16,240 kg (35,810 lb). Treat that figure as the paver and screed together, not the screed alone, and confirm isolated screed weight with your dealer if it matters for transport or crane picks.

What replaced the Caterpillar AS3251C?

No documented one-for-one successor carries the AS3251C name forward. Cat's current paver platforms — the AP600, AP1000, and AP1055 class — ship factory-fit with the newer SE-series screeds instead of a continued Extend-A-Mat AS-series line. The SE-series is the modern factory replacement for the role the AS3251C filled, not a direct badge-engineered successor.

What AS3251C owners discuss

The AS3251C extenders keep losing alignment mid-shift even after they're set correctly. What's going on?

This is a recognized complaint on Extend-A-Mat electric screeds, not just the AS3251C. Operators report setting extension plates dead level, then watching them creep out of alignment once material load hits the extensions, sometimes ending in a loud bang followed by vertical movement in the extension. Root cause is usually worn or dirty extender slide bushings, a extension tube that's scored from debris packed into the slide path, or (less common but reported) a frame that was never square from the factory. Check the extender tubes for scoring and clean out packed dirt before blaming the bushings. If plates won't stay closed after cleaning and adjustment, have your dealer verify the screed frame is square and the tow points aren't bent.

How much wear is normal on the screed plates before they need replacing, and where does it show up first?

Screed plates wear from the bottom, and the wear typically shows first about 100-150 mm (4-6 in) in from the trailing edge as a shallow indentation or ripple rather than uniform thinning. Check thickness daily with calipers or a micrometer against the minimum thickness in the maintenance manual — don't eyeball it, since a plate that looks fine from above can already be under spec. Wear concentrated near the front or rear edge instead of centered usually points to a twisted screed frame or a leveling issue rather than normal plate wear, so don't just swap plates and move on if the wear pattern looks lopsided.

The vibrators on the extenders seem to be running rough or noisy compared to the main screed. Is that a common wear point?

Yes. The extension vibrators are synchronized hydraulically to match the main screed's frequency and amplitude, and their bearings/shafts see the same abrasive exposure as the main screed but in a smaller, harder-worked package. Oil-bath vibratory pods run cooler and last longer than grease-packed ones, so check oil level and condition in the pods regularly rather than waiting for noise. A rough or humming extender vibrator usually means bearing wear on the shaft, and running it that way long-term will telegraph into the mat as an uneven texture on the widened section. Have your dealer verify shaft and bearing condition before it fails completely and takes the pod housing with it.

Is electric screed heating on the AS3251C prone to uneven heat across the plates?

Uneven heating is one of the most common complaints on electric screed heat, and it's almost always a handful of dead or partially dead heating elements rather than a wiring fault. Use a temperature gun across the width of the plates before paving — three or more check points — to catch a cold spot before it tears the mat. Corroded or loose terminals at the element connections and blown individual fuses to specific heat strips are the usual culprits, and they're easy to miss visually since the rest of the screed heats normally. Give the screed the full warm-up time before pulling mix; a cold plate from impatience gets blamed on the heating system when the elements are actually fine.

What condition should the hydraulic hoses and quick-disconnects be in where the screed hooks to the tow tractor?

Since the AS3251C has no hydraulics of its own, everything — extension drive, vibrators, leveling, heat circuit if hydraulically assisted — runs off hose runs and quick-disconnect couplers back to the host paver's hydraulic system. Weeping at a quick-disconnect is common and usually an o-ring problem in the coupler or plug rather than a hose fault; swap the mating hose to the other port and see if the leak follows the plug (plug problem) or stays put (coupler problem) before replacing anything. Check couplers for pitting from moisture sitting in the o-ring groove, and always wipe and lightly lubricate the plug before reconnecting to avoid tearing a new o-ring on first mate. A screed that won't hold extension position under load can be a coupler that's not fully seating rather than a mechanical fault in the extender itself.

Owners mention crown problems on the mat edges. Is that a screed setup issue or a sensor issue?

Both get blamed, but check mechanical crown setting first. Too much crown on the leading edge produces an open, rough texture along the mat edges; too little crown produces the opposite — an open texture down the center. If crown is set correctly and the edges still finish inconsistently, look at the slope/grade sensor calibration on the tow arm side — it's a fluid-filled sensor similar to a spirit level and it does drift out of calibration, especially after transport or a hard knock. Also give the screed time to react after any angle-of-attack change; it can take multiple tow-arm-lengths of travel before the mat settles at the new thickness, so operators chasing the level every few meters will chase it forever and blame the sensor for what's actually settling time.

What should I check before buying a used AS3251C screed?

Check screed plate thickness against minimum spec at multiple points, not just visually — look specifically 100-150 mm in from the trailing edge where wear shows first. Run the extension slides in and out full travel checking for scoring, binding, or play in the bushings; binding thickness-control screws are a tell for worn bushings. Confirm the extender and main-screed vibrators run smooth and quiet with no play in the shafts. Test the electric heat across the full width with a temp gun for cold spots or dead elements, and inspect wiring and connectors for corrosion. Check every quick-disconnect coupler for pitting or weeping and confirm the hose set is complete and not swapped with mismatched fittings. Finally, confirm the screed's mounting and hydraulic/electric interface actually matches the host tractor you plan to run it on — Extend-A-Mat screeds are matched to specific paver hydraulic and control configurations, and a mismatch isn't always obvious until it's on the machine. Have your dealer verify frame squareness and tow-point condition before you commit, since a twisted frame won't show up in a quick walk-around.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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