Recognize Hitch Load and Load Distribution
- Relate center of gravity and axle placement to hitch load.
- Distinguish hitch-load recommendations by hitch type.
- Explain how end loading and uneven loading affect handling.
- Trailer tongue-weight scale — Measure conventional hitch load within the scale's rated capacity.
- Vehicle wheel-load scales — Measure supported loads and compare side-to-side loading using equipment rated for the trailer.
- Tape measure — Compare axle position against consistent frame reference points during a tracking inspection.
- Flashlight — Inspect spring arch, axle attachments and cargo placement.
- Wheel chocks — Secure the trailer against rolling during stationary inspection and weighing preparation.
The center of gravity is the point at which the vehicle's weight can be considered concentrated. Both its lengthwise and side-to-side position matter when locating the running gear and establishing weight distribution.
Axle placement relative to the center of gravity determines how the trailer load is divided between the hitch and running gear. Dexter recommends conventional bumper-hitch weight of 10% to 14% of gross vehicle weight and fifth-wheel or gooseneck hitch weight of 15% to 20%. These source recommendations are not universal values; values vary by maker.
Concentrating weight at the trailer's ends can harm handling even when hitch weight is within the recommended proportion. Polar inertia and frame flex can produce dynamic loading beyond the loads expected under static conditions.
Uneven side-to-side loading can also affect tracking. As a leaf spring carries more load, its arch flattens and its length increases. Because the axle is attached near the spring's midpoint, unequal spring deflection can skew the axle relative to the trailer centerline.
How It Works
Center of gravity and load sharing
The center of gravity is the point at which the trailer's weight can be considered concentrated; its lengthwise and side-to-side positions both matter. Axle placement relative to that point determines how the load is shared between the hitch and running gear. Moving cargo changes the center of gravity and can change hitch load without changing total trailer weight.
Hitch recommendations and their limits
Dexter recommends conventional bumper-type hitch load of 10%–14% of gross vehicle weight, with a running-gear share of 86%–90%. For fifth-wheel or gooseneck trailers, the recommendations are 15%–20% of gross vehicle weight at the hitch and 80%–85% at the running gear; values vary by maker. Concentrating cargo at the ends increases resistance to changes in rotational motion, while frame flex can create dynamic loads that a stationary weight reading does not reveal.
Uneven loading and tracking
As a leaf spring carries more load, its arch flattens and its length increases. Because the axle attaches near the spring's midpoint, unequal spring deflection can skew the axle relative to the trailer centerline. A tracking complaint therefore calls for checking side-to-side load distribution rather than assuming the axle is bent.
Step-by-Step Procedure
0/6 doneDexter load-distribution recommendations; values vary by maker
| Conventional bumper-type hitch load | 10%–14% of gross vehicle weight |
| Running-gear share with conventional hitch | 86%–90% |
| Fifth-wheel or gooseneck hitch load | 15%–20% of gross vehicle weight |
| Running-gear share with fifth-wheel or gooseneck hitch | 80%–85% |
Diagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| Conventional bumper-hitch load appears too light or too heavy. | Identify the hitch type, measure loaded hitch weight and gross trailer weight, and compare their proportion with the applicable maker's guidance. Review cargo position relative to the axle before changing the load. | Dexter conventional bumper-type recommendation: 10%–14% of gross vehicle weight; running-gear share: 86%–90%. Values vary by maker. | The center of gravity is positioned so that the hitch and running gear carry an unsuitable division of load. Basis: applications-manual-(lit-008-00) |
| Fifth-wheel or gooseneck load distribution is being judged using bumper-hitch guidance. | Confirm the coupling type and compare measured hitch and running-gear loads with guidance applicable to that trailer. | Dexter fifth-wheel or gooseneck recommendation: 15%–20% of gross vehicle weight; running-gear share: 80%–85%. Values vary by maker. | The wrong hitch-type recommendation has been applied. Basis: applications-manual-(lit-008-00) |
| Handling remains poor despite an acceptable hitch-weight proportion. | Inspect whether heavy cargo is concentrated at the trailer's ends. Consider end loading and frame flex rather than treating the stationary hitch reading as proof of acceptable handling. | An acceptable hitch-weight proportion does not eliminate handling problems caused by end loading, frame flex or uneven side-to-side loading. | End concentration increases polar inertia, and frame flex can produce dynamic loading beyond static conditions. Basis: applications-manual-(lit-008-00) |
| Trailer tracks poorly with visibly unequal spring deflection. | Compare side-to-side cargo placement, supported loads and spring arch. Check axle position relative to consistent frame references and reassess after correcting uneven loading. | Unequal spring deflection can skew the axle relative to the trailer centerline; the lesson provides no alignment tolerance. | The more heavily loaded leaf spring flattens and lengthens, potentially changing axle orientation. Basis: applications-manual-(lit-008-00) |
At the Bay: Diagnose the Case
CASE 1 / 4
Conventional bumper-hitch load appears too light or too heavy.
- Test
- Compare
- Correct
Select the next check
Basis: applications-manual-(lit-008-00). A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Treating Dexter recommendations as universal maker requirements.
- ✕ Confusing hitch-weight proportion with an absolute load rating.
- ✕ Assuming acceptable hitch weight guarantees acceptable handling.
- ✕ Condemning an axle before checking uneven loading and spring deflection.
Quick Check
Practice only — not scored.
Plan the Service Sequence
Planning practice only. Follow the applicable manufacturer's instructions, employer safety program and qualified supervision on real equipment.
Plan the first action. Compare the service steps with the bay mistakes.
Source: applications-manual-(lit-008-00) — 4-7