Quick Facts

  • Manufacturer: Fontaine Fifth Wheel
  • Product Series: No-Slack 6000
  • Product Type: Lightweight stamped-steel fifth wheel
  • Duty Classification: Standard to moderate-duty on-highway service
  • Mounting Options: Sliding and stationary mounting systems
  • Maximum Vertical Load: 50,000 pounds
  • Maximum Drawbar Pull: 150,000 pounds
  • Recommended Maximum GCW: Less than 115,000 pounds
  • Kingpin Compatibility: Standard 2-inch SAE kingpin
  • Release Options: Manual or air actuated
  • Primary Applications: Highway tractors, tankers, regional tractors, and weight-sensitive fleets
  • Production Status: Current product with multiple mounting configurations

Overview

The Fontaine No-Slack 6000 is a lightweight stamped-steel fifth wheel designed for standard and moderate-duty on-highway tractor-trailer applications. It combines Fontaine’s self-adjusting No-Slack locking mechanism with a weight-saving top-plate design.

The locking mechanism automatically adjusts around the trailer kingpin as normal wear occurs. This helps control movement between the tractor and trailer, providing a smoother ride while reducing impact loading and component wear.

The 6000 can be combined with several Fontaine sliding and stationary mounting systems. Its relatively low weight makes it suitable for fleets trying to preserve payload without sacrificing the capacity required for normal highway operations.

Key Characteristics

  • Lightweight stamped-steel top plate
  • Patented self-adjusting No-Slack locking mechanism
  • Positive secondary lock
  • Locking trigger designed to reduce high coupling
  • 50,000-pound vertical-load rating
  • 150,000-pound drawbar-pull rating
  • Standard 2-inch kingpin compatibility
  • Manual and air-actuated release options
  • Sliding and stationary mounting choices
  • Designed for on-highway operation

Major Components

  • Stamped-steel top plate
  • Fifth-wheel throat
  • Self-adjusting lock
  • Wedge and wedge-stop rod
  • Locking trigger
  • Positive secondary lock
  • Operating handle and pull handle
  • Pivot pins and bushings
  • Mounting brackets
  • Slider rails and locking components when equipped
  • Optional air-release cylinder and controls
  • Lubrication points

Coupling Type and Design

The No-Slack 6000 is a conventional semi-oscillating fifth wheel with a pressed or stamped-steel top plate. Its front-to-rear articulation allows the tractor and trailer to move across normal road grades and transitions.

The 6000 uses Fontaine’s self-adjusting lock to maintain close contact with a standard 2-inch trailer kingpin. It is intended for standard and moderate-duty highway service rather than severe off-highway or extreme heavy-haul applications.

How the Coupling System Works

As the tractor backs beneath the trailer, the kingpin enters the fifth-wheel throat and activates the locking trigger. The lock closes around the kingpin, while the positive secondary lock helps prevent unintended release.

The No-Slack mechanism automatically compensates for normal wear by keeping the lock closely adjusted to the kingpin. This reduces free movement that can otherwise create impact loads, noise, and an uneven tractor-trailer ride.

Position and Function Within the Vehicle

The fifth wheel mounts above the tractor’s rear frame and axle group. It supports the front of the semitrailer, captures its kingpin, transfers pulling and braking forces, and permits controlled articulation between the tractor and trailer.

Common Specifications

  • Construction: Stamped high-strength steel
  • Maximum Vertical Load: 50,000 pounds
  • Maximum Drawbar Pull: 150,000 pounds
  • Maximum Recommended GCW: Less than 115,000 pounds
  • Approximate Top-Plate Weight: Approximately 205 pounds; configuration may affect weight
  • Kingpin Size: 2 inches
  • Service: Standard to moderate-duty on-highway use
  • Release: Manual or optional air actuation
  • Mounting: Compatible Fontaine sliding or stationary mount
  • Mounting height, slide travel, release configuration, weight, and complete assembly number depend on the selected mounting system.

Load Ratings and Operating Capacity

The No-Slack 6000 is rated for a maximum vertical load of 50,000 pounds and a maximum drawbar pull of 150,000 pounds. Fontaine classifies it for standard to moderate-duty on-highway service with a gross combination weight below 115,000 pounds.

The complete vehicle remains limited by its lowest-rated component, including the tractor frame, mounting system, axles, suspension, tires, wheels, kingpin, trailer upper coupler, and completed vehicle ratings.

Articulation and Oscillation

The top plate pivots forward and rearward to accommodate normal tractor-trailer movement. It is not a fully oscillating fifth wheel and does not provide the side-to-side articulation required by certain rough-terrain and specialized heavy-haul applications.

Sliding and Adjustment System

The 6000 can be installed on Fontaine air-slide systems or stationary mounts. Depending on the selected slider, adjustment may be available in two-inch or four-inch increments.

A sliding installation allows the driver to change tractor-to-trailer clearance and redistribute weight between the steering and drive axles. Before travel, every slider lock must be fully engaged and visually inspected.

Release and Locking Mechanism

The patented No-Slack mechanism automatically adjusts to the trailer kingpin. A positive secondary lock can only be released through the operating handle, while the locking trigger helps reduce the risk of high coupling.

Fontaine states that approximately 65 pounds of pull force is required to open the lock. Air-actuated models are also available for compatible applications.

Air and Electronic Controls

Manual-release configurations do not require air or electronic controls. Air-actuated models require a compatible pneumatic supply, protected air lines, an actuator, and correctly installed controls.

Air-operated sliders also use pneumatic controls to disengage their locking mechanism. Air actuation does not replace visual inspection, a pull test, or approved coupling and slider procedures.

Mounting and Installation

The fifth wheel must be installed using a Fontaine-approved mounting system and procedures appropriate for the tractor frame. Installation must preserve frame strength, fastener security, trailer swing clearance, tire clearance, and access to the release mechanism.

Vehicle Frame and Mounting Compatibility

Compatibility depends on:

  • Tractor manufacturer and model
  • Frame width and rail construction
  • Rear-axle and suspension arrangement
  • Required fifth-wheel height
  • Slider travel and mounting length
  • Trailer swing and landing-gear clearance
  • Vehicle weight distribution
  • Intended operating duty

Mating Component and Trailer Compatibility

The No-Slack 6000 must be paired with an approved 2-inch SAE kingpin and compatible trailer upper-coupler plate. The kingpin, upper coupler, trailer structure, and fifth wheel must all meet the required load ratings and wear limits.

Common Applications

  • Over-the-road tractors
  • Regional-haul tractors
  • Dry-van operations
  • Refrigerated-freight operations
  • Tanker tractors within approved ratings
  • Weight-sensitive fleets
  • Standard and moderate-duty highway service

Advantages

  • Lightweight stamped-steel construction
  • Self-adjusting kingpin lock
  • Reduced slack between tractor and trailer
  • Positive secondary lock
  • High-coupling protection through the locking trigger
  • Sliding and stationary mounting choices
  • Manual and air-release options
  • Established replacement-parts support

Limitations or Considerations

  • Restricted to approved on-highway applications
  • Not intended for severe off-highway service
  • Recommended GCW is below 115,000 pounds
  • Top plate requires regular lubrication
  • Lock and wedge-stop adjustment require inspection
  • Slider systems add maintenance points
  • Does not provide full side-to-side oscillation
  • Does not increase the tractor’s certified ratings

Driver and Operator Experience

The self-adjusting lock helps reduce movement, noise, and impact between the tractor and trailer. On sliding models, the driver can reposition the fifth wheel to adjust axle loading and trailer clearance.

Drivers must still verify every coupling through visual inspection and a controlled pull test. Slider locks must also be inspected after every adjustment.

Coupling and Uncoupling Procedure

Before coupling, inspect the top plate, lock, kingpin, upper coupler, mounting system, and lubrication. Set the trailer height so its upper-coupler plate contacts the lower portion of the fifth wheel as the tractor backs underneath.

After coupling:

  • Perform a controlled pull test
  • Visually confirm the lock is closed around the kingpin
  • Confirm the secondary lock is engaged
  • Verify there is no gap between the mating plates
  • Connect and inspect the trailer air and electrical lines

These steps are an overview and do not replace Fontaine instructions or fleet safety procedures.

Inspection and Wear Points

  • Lock and kingpin contact surfaces
  • Wedge and wedge-stop rod
  • Locking trigger and secondary lock
  • Operating and pull handles
  • Top-plate surface and throat
  • Pivot pins and bushings
  • Mounting brackets and fasteners
  • Slider rails, wedges, and stops
  • Air lines and actuators when equipped
  • Trailer kingpin and upper coupler

Lubrication Requirements

The top plate, locking mechanism, pivot points, and applicable slider components require the lubricant and service intervals specified by Fontaine. Cold-weather service may require cleaning away hardened or contaminated grease before fresh lubricant is applied.

Maintenance and Ownership Notes

Regular maintenance includes cleaning, lubrication, lock inspection, wedge-stop rod adjustment, fastener inspection, and measurement of the kingpin and locking components. Use the complete model number when ordering rebuild kits or individual components.

Common Coupling Problems

  • High coupling: Incorrect trailer height allows the kingpin to pass above the locking mechanism.
  • Failure to lock: Contamination, damaged parts, binding, poor lubrication, or incorrect trailer height may prevent engagement.
  • Difficult release: Pressure against the lock, dry components, damage, or improper adjustment may restrict the handle.
  • Excessive kingpin movement: A worn kingpin, lock, wedge, or incorrectly adjusted wedge-stop rod may create slack.
  • Slider will not move or lock: Low air pressure, corrosion, damaged wedges, rail contamination, or tractor-trailer binding may be responsible.
  • Air-release failure: Damaged air lines, low pressure, a faulty valve, or actuator problems may prevent release.

Safety and Service Precautions

Never rely on handle position alone to confirm coupling. Perform a visual inspection and pull test before moving the vehicle. Secure and support the trailer before uncoupling or servicing the fifth wheel.

Do not exceed Fontaine’s ratings or substitute unapproved components. Welding, heating, grinding, or modifying structural parts can damage the fifth wheel and invalidate its approved capacity.

Identification Information

Record the following information before ordering parts or a replacement assembly:

  • Fontaine model and assembly number
  • Top-plate part number
  • Manual or air-release configuration
  • Sliding or stationary mount
  • Mounting height and slide travel
  • Bracket and rail design
  • Vehicle identification number
  • Kingpin size and condition

Buying Considerations

  • Confirm that the application is on-highway
  • Verify vertical-load, drawbar-pull, and GCW requirements
  • Choose sliding or stationary mounting
  • Confirm mounting height and required slide travel
  • Select manual or air-actuated release
  • Verify tractor-frame compatibility
  • Check trailer swing and landing-gear clearance
  • Confirm genuine replacement-parts availability

Variants and Configurations

Common No-Slack 6000 configurations include:

  • 6000 NWB lightweight air-slide assembly
  • 6000 LWB lightweight air-slide assembly
  • 6000 PML adjustable stationary mount
  • 6000 BSL weight-saving fixed mount
  • Manual-release top plate
  • Air-actuated release top plate
  • Different mounting heights and slider travels

Complete assembly numbers must be used because top plates, brackets, mounting heights, and controls are not automatically interchangeable.

Comparison to Similar Equipment

Compared with the Fontaine No-Slack 7000 Fifth Wheel, the 6000 uses a lighter stamped-steel plate and has lower vertical-load and application ratings.

Compared with the Fontaine No-Slack H7 Fifth Wheel, the 6000 is intended for lighter on-highway duty rather than severe-duty and off-highway operation.

Compared with the Holland FW17 Lightweight Fifth Wheel, the No-Slack 6000 uses Fontaine’s self-adjusting lock and Fontaine mounting-system options.

Best Fit For

  • Standard and moderate-duty highway tractors
  • Combinations below Fontaine’s stated GCW limit
  • Fleets prioritizing fifth-wheel weight savings
  • Dry-van and refrigerated operations
  • Approved tanker applications
  • Fleets wanting a self-adjusting kingpin lock

Related Vehicle and Trailer Types

Related Truck and Trailer Models

Related Coupling Types

Related Coupling Products

Related Equipment Systems

Related Guides

Regulatory and Compliance Notes

The fifth wheel and mounting system must comply with applicable commercial-vehicle requirements. Its rating does not override the truck’s axle, frame, suspension, tire, wheel, kingpin, trailer, or certified gross weight ratings.

Real World Operating Notes

The No-Slack mechanism can reduce chucking between the tractor and trailer, but it cannot compensate for an excessively worn kingpin or neglected fifth wheel. Coupling inspections, lubrication, and wear measurements remain essential.

When a slider is fitted, axle weights should be confirmed on a certified scale after adjustment. The driver must also verify that trailer swing and landing-gear clearances remain adequate.

Frequently Asked Questions

What is the Fontaine No-Slack 6000?

It is a lightweight stamped-steel fifth wheel for standard and moderate-duty on-highway tractor-trailer applications.

What are its load ratings?

Fontaine rates it for a 50,000-pound vertical load and 150,000-pound drawbar pull.

What does No-Slack mean?

The locking mechanism automatically adjusts around the kingpin to control free movement as normal wear occurs.

Can it be installed on a slider?

Yes. Fontaine offers compatible sliding and stationary mounting systems.

Is an air release available?

Yes. Manual and air-actuated top-plate configurations are available.

Can it be used off highway?

Fontaine classifies the 6000 for approved on-highway service. Severe or off-highway applications require a more suitable fifth wheel.

Does the self-adjusting lock eliminate maintenance?

No. The lock, wedge-stop rod, kingpin, top plate, pivot points, mount, and slider still require inspection and maintenance.

How are the correct replacement parts identified?

Use the complete Fontaine assembly number, top-plate number, mounting type, release configuration, height, and slide travel.

Availability and Where to Find

Fontaine No-Slack 6000 assemblies and replacement parts are available through Fontaine distributors, commercial-truck dealers, fleet-parts suppliers, fifth-wheel specialists, and heavy-duty repair facilities.

Current specifications, literature, parts information, instructional material, and distributor resources are available through the official Fontaine No-Slack 6000 page.

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