29/12/2005
For many motorhome enthusiasts in the UK, the Workhorse chassis represents a bygone era of robust and reliable RV foundations. Known for their sturdy build and enduring performance, these chassis, particularly the P Series and W Series, incorporated a sophisticated braking system designed for safety and convenience. Understanding the nuances of these systems, especially the unique parking brake, is crucial for any owner looking to maintain their vehicle's integrity and ensure peace of mind on the open road.
While Workhorse chassis are no longer in production for RVs, their legacy lives on in countless motorhomes across the country. This article delves deep into the specific type of parking brake utilised by Workhorse, its complex operation, and addresses some of the common brake-related issues that owners might encounter. By demystifying these vital components, we aim to empower you with the knowledge to keep your Workhorse-equipped RV performing optimally.
The Workhorse Automatic Apply Parking Brake System
Workhorse P Series (16,500 lb., 17,000 lb., 18,000 lb. GVWR) and W Series (18,000 lb. and 24,000 lb. GVWR) chassis feature a distinctive automatic apply parking brake system. This innovative design is spring-applied, meaning the brake automatically engages by spring tension, and hydraulic-released, requiring hydraulic pressure to disengage it. The entire operation is managed by an electric/hydraulic parking system that controls a propeller shaft-mounted parking brake.
Workhorse utilised two primary designs for this automatic apply park brake system: the J71 and the J72. The J71 system was standard on all P Series 16,500 lb., 17,000 lb., and 18,000 lb. GVWR chassis through the 2004 model year. From the 2005 model year onwards, the 17,000 lb. and 18,000 lb. P Series chassis, along with all W Series 24,000 lb. GVWR chassis, were equipped with the more advanced J72 system. While both systems share the core principle of automatic application and hydraulic release, their specific components and operational nuances differ.
J71 Parking Brake Operation and Components
The J71 system, found on earlier P Series chassis, incorporates an internal expanding parking brake. Its operation relies on a precise sequence of electrical and hydraulic actions. To release the brake, the driver moves the shift lever on the steering column out of the 'Park' position. This action opens the circuit to the park/neutral switch, which in turn closes the park/neutral relay. This allows current to flow to the solenoid valve, causing it to close and maintain system pressure. Concurrently, the park/neutral relay supplies current to the park brake pump motor switch (also known as the pressure maintenance switch).
Should the system pressure drop below 1200 psi, the park brake motor switch closes, activating the electric/hydraulic pump. This pump then supplies fluid pressure to the actuator. The actuator houses a large spring that, when unopposed, applies the parking brake. However, the hydraulic fluid pressure generated by the pump overcomes this spring tension, causing the piston within the actuator to move. This movement is transferred via the parking brake cable, releasing the brake. Once the fluid pressure reaches approximately 1600 psi, the park brake motor switch opens, and the pump shuts off, with the solenoid valve maintaining the pressure.
Applying the parking brake is equally straightforward. Returning the shift lever to 'Park', turning off the ignition, or pulling the manual push/pull switch on the instrument panel will de-energise the solenoid valve. This allows fluid to return to the reservoir, causing the system pressure to decrease. As the pressure drops, the spring tension inside the actuator overcomes the reduced hydraulic force, moving the piston and applying the parking brake through the cable.
Key Components of the J71 System:
- “AUTO PARK” WARNING LAMP: This crucial indicator illuminates when system pressure falls below 450 psi or when the electric/hydraulic pump is running due to the park brake motor switch being closed. It flashes at partial release pressures, alerting the driver to potential issues.
- PARKING BRAKE LIGHT SWITCH: Located on the back of the actuator assembly, this switch controls the ground side of the “AUTO PARK” lamp. It closes when system pressure is below 450 psi, turning on the light when the ignition is on.
- PARKING BRAKE PUMP ASSEMBLY: This assembly, consisting mainly of an electric pump and fluid reservoir, provides the necessary fluid pressure. Its location varied by model year: on 1999 and 2000 chassis, it was in a component box on the passenger side, behind the transmission. For 2001 and 2002 models, it was relocated to the front driver’s side of the radiator core support. A pressure relief valve within the pump limits system pressure to 1800 psi.
- PARK BRAKE MOTOR SWITCH (Pressure Maintenance Switch): Mounted to the pump assembly housing, this hydraulic pressure switch controls the pump motor. It closes below 1200 psi, activating the pump, and opens around 1600 psi, turning it off. It applies B+ voltage to the park brake motor relay.
- PARKING BRAKE SOLENOID VALVE: This solenoid and valve assembly controls fluid return to the pump reservoir. When the brake is released, it closes to hold pressure. When applied, it opens to allow fluid return, facilitating brake engagement. Its location mirrored that of the pump assembly.
- ACTUATOR: A spring-loaded device located on the inside of the right frame rail (in the component box for earlier models), the actuator is the mechanical heart of the system. Its internal spring applies the brake, while hydraulic pressure applied against its piston overcomes this spring to release it.
- PARK/NEUTRAL POSITION SWITCH: Situated on the left side of the transmission, this switch detects the gear selector position. In 'Park', it's closed, supplying current to the park/neutral relay, which opens the circuit to the park brake motor switch and solenoid valve. Moving out of 'Park' opens this switch, allowing the park/neutral relay to close and supply current to the pump motor switch and solenoid valve.
- PARK BRAKE PULL SWITCH: A manual override switch on the instrument panel. Normally pushed in (closed), pulling it opens the circuit to the park/neutral relay and solenoid valve, dumping pressure and applying the brake.
- PARK BRAKE PUMP MOTOR RELAY: This relay, located with the pump assembly, receives B+ from the park brake motor switch. It acts as the automatic control circuit for the high voltage current required to run the pump motor, closing contacts to power the pump when needed.
J72 System
While specific operational details for the J72 system were not provided, it's understood to be an evolution of the J71, offering similar automatic apply and hydraulic release functionality. It was integrated into later P Series and all W Series 24,000 lb. GVWR chassis, indicating improvements or adaptations for heavier-duty applications.
Do Workhorse Brakes Have Problems?
The Chevrolet Workhorse chassis earned a strong reputation for durability and was a favourite among many RV manufacturers, succeeding the venerable P-30 and P-32 chassis. However, like any complex mechanical system, Workhorse brakes, despite their general reliability, have experienced some issues over time.
It's important to note that the Workhorse chassis, particularly for RV applications, has been discontinued. This can sometimes lead to challenges in sourcing specific parts, although a network of dealerships and parts suppliers still exists to serve existing owners.
Workhorse Chassis Brake Problems: Common Concerns
While many Workhorse chassis owners report trouble-free experiences with their brakes, some have encountered minor issues. A significant event was a recall in 2006, addressing specific concerns, though the details of that recall's scope are not fully outlined here.
Reported minor problems have included:
- Bad or dirty ABS sensors: These sensors are crucial for the Anti-lock Braking System (ABS) to function correctly. Contamination or failure can lead to ABS warning lights or impaired braking performance.
- ABS indicator light malfunctions: The warning light might illuminate erroneously, indicating a sensor issue even if the braking system is otherwise functional.
- Specific front brake difficulties: One common report involves issues with a front brake, potentially due to a collapsing hose or the wheel assembly overheating during operation.
For front brake issues where the caliper might be sticking, a simple maintenance tip often suggested by experienced owners involves:
- Loosening the bolts on the slide pins.
- Gently tapping the calipers. This can help them slide back into their correct position, improving brake function.
- When re-tightening, it is crucial to tighten the lead or top bolt first. This is a mandatory step for proper reassembly.
- Ensure the flats on the slide pin are correctly positioned. Misalignment here can lead to continued brake trouble.
Notably, this particular 'easy fix' often does not require jacking up the RV, making it a more accessible maintenance task for owners.
Despite these occasional complaints and the 2006 recall, the consensus among owners generally points to Workhorse brakes being very reliable and possessing strong stopping power when properly maintained. The issues reported tend to be minor and resolvable rather than systemic failures.
Understanding Your Workhorse Chassis
The Workhorse chassis underwent several design evolutions. Around 2000, Workhorse widened the track on the P32 series, aligning the front tyres with the outer rear tyres, which was intended to improve performance. In 2005, the W Series was introduced, using a two-digit nomenclature to indicate safe towing capacity in thousands of pounds. A key design change for the W Series was the implementation of leaf springs on all four corners, enhancing ride comfort. Beyond the gas-powered W Series, Workhorse also introduced a rear-diesel R Series and a rear-engine UFO Series, specifically for motorhome applications.
Is Workhorse Chassis Still in Business?
Workhorse Group Inc. did face significant challenges during the 2009 economic downturn and was believed to have ceased RV chassis production. However, the company made a comeback around 2015, planning to re-enter the chassis market. In recent years, Workhorse has significantly diversified its focus, moving into the production of chassis for electric vehicles, delivery vans, and even components for drones and helicopters. Their headquarters are in Ohio, with manufacturing in Indiana. While they produce electric-powered pickup trucks (like the W-15) and electric delivery vans, their website provides little current information about new RV chassis production.
The company is owned by AMP Electric Vehicles, which largely explains this shift towards electric transportation. This new direction means that finding specific new parts for older Workhorse RV chassis can sometimes be challenging, requiring owners to rely on the aftermarket or specialised dealers.
Motorhomes with Workhorse Chassis
Many prominent RV manufacturers utilised the Workhorse chassis for their motorhome lines, a testament to its quality. Examples include Winnebago (e.g., the Adventurer model), Sportscoach, and Fleetwood (e.g., the 2002 Southwind). These motorhomes were often praised for their towing capabilities, handling of rough terrain, and overall robust performance, reinforcing the Workhorse chassis's reputation for durability.
How to Find Out Which Workhorse Chassis You Have
The most accurate method to determine your specific Workhorse chassis model is by conducting a VIN (Vehicle Identification Number) search. The VIN contains encoded information about your vehicle's specifications, including the chassis type. Unfortunately, the official Workhorse website no longer provides direct support or information for their older RV chassis. Owner's manuals are another excellent resource, often containing detailed information about all components. If these options are unavailable or yield no results, consulting a qualified RV dealer or technician is your best bet, as they can often decipher the information or physically inspect the chassis.
Workhorse Chassis vs. Competitors (Freightliner & Ford)
When comparing Workhorse chassis to contemporaries like Freightliner or Ford, opinions often vary significantly, largely due to subjective experiences and the myriad of other components influencing overall RV performance.
- Workhorse vs. Freightliner: Some owners found Freightliner chassis to offer a smoother ride, less cabin noise, and better manoeuvrability, potentially even yielding better fuel economy (e.g., 10.2 mpg for Freightliner vs. 7.2 mpg for Workhorse in some anecdotal reports). Others preferred Workhorse for its perceived overall performance and sturdiness.
- Workhorse vs. Ford: Similar to Freightliner, preferences between Workhorse and Ford chassis often come down to individual experience. Factors like ride firmness, handling characteristics, and reliability can differ greatly depending on the specific RV model, its weight distribution, axle ratings, and the quality of other integrated components.
Ultimately, the "better" chassis is often a matter of personal preference and the specific design and build of the entire motorhome. While certain chassis might have known design strengths or weaknesses at different times, the overall performance and durability you experience are a result of many interconnected factors.
Frequently Asked Questions (FAQs)
What type of parking brake does a Workhorse chassis use?
Workhorse P Series and W Series chassis utilise an automatic apply parking brake system. This system is spring-applied (engages via spring tension) and hydraulic-released (requires hydraulic pressure to disengage). It's controlled by an electric/hydraulic system and mounts to the propeller shaft.
Are Workhorse chassis still manufactured for RVs?
No, Workhorse chassis are largely discontinued for new RV production. The company has shifted its focus to manufacturing chassis for electric vehicles, delivery vans, and other electronic components under the ownership of AMP Electric Vehicles.
Are Workhorse brakes reliable?
Generally, Workhorse brakes are considered very reliable by many owners, offering strong stopping power. While there was a recall in 2006 and some owners report minor issues like ABS sensor problems or occasional sticking calipers, these are typically resolvable and do not detract from the overall robustness of the system.
How can I identify my Workhorse chassis model?
The most accurate way is to perform a VIN (Vehicle Identification Number) search. You can also check your RV's owner's manual. If these options are not fruitful, an experienced RV dealer or technician should be able to help you identify the specific chassis.
What are common Workhorse brake issues?
Common minor issues reported include bad or dirty ABS sensors, ABS indicator light malfunctions, and specific front brake issues such as a collapsing hose or overheating. Simple maintenance, like checking and lubricating slide pins, can often address some of these problems.
Final Thoughts
The Workhorse chassis, though no longer in active production for recreational vehicles, remains a testament to durable engineering. Its unique automatic apply parking brake system, whether the J71 or J72 design, was a sophisticated feature aimed at enhancing safety and ease of use. While minor brake-related issues can arise, as with any vehicle, the overall reliability and stopping power of Workhorse brakes are well-regarded.
For owners of these enduring motorhomes, understanding the intricacies of their braking system and knowing how to identify their specific chassis model through a VIN search or owner's manual is invaluable. Despite the company's shift towards electric vehicles, the legacy of the Workhorse chassis continues, providing a solid foundation for countless adventures on the road.
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