Whether a simple bolt-through-hole arrangement in aluminum will suffice for 2000 deployment cycles depends on a few key factors: load magnitude, frequency of actual rotation under load, and tolerance for “slop” (wear-induced play) over time. In many low-cycle hinge applications, a partially threaded bolt riding directly in an aluminum hole can work fine—but only if sized and installed carefully. Below are the main considerations:
1. Contact Stress & Wear
- Bearing Surface
The unthreaded portion of the bolt must be the surface in contact with the bracket holes—so the bracket is not riding on the bolt’s threads. If the threaded portion rubs against the aluminum, wear will accelerate dramatically. - Hole Diameter Tolerance
A good rule of thumb is to keep the clearance between the hole ID and the bolt shank as small as practical. Excessive clearance increases dynamic loading (slamming back and forth) and wear. - Load & Rotation
If your stabilizer leg mostly sees static load and only rotates during deployment (a relatively slow and infrequent motion), there will be far less sliding wear than in a continuously pivoting joint. In many caravan stabilizer setups, the leg is deployed a few hundred (or low thousands) of times over its life—usually at a fairly gentle rate of motion. That can tip the balance in favor of the simpler solution.
2. Materials & Corrosion
- Steel Bolt / Aluminum Bracket
Aluminum is softer than steel, so over time you may see some elongation or ovalizing of the holes, especially if the hinge sees shock or vibration. - Galvanic Corrosion
Standard zinc-plated steel in aluminum is not typically a severe galvanic couple if kept relatively clean and dry, but if you anticipate exposure to salt or moisture, a stainless bolt or a protective coating is wise. (Note that some grades of stainless can still cause galvanic corrosion with aluminum in salty environments, so consider isolation washers or anti-seize.)
3. Bushings / Sleeves vs. Simple Bolt
- Why Bushings?
A sacrificial steel or bronze bushing pressed into the aluminum bracket does two things:- It prevents wear on the more expensive, difficult-to-replace bracket.
- It can be replaced if/when wear occurs.
- Bearing or Pivot Sleeve
If you really need to preserve a tight, low-friction pivot over many cycles, a bronze or engineered plastic bearing is a more reliable approach. - Trade-Off
Bushings do add complexity (and cost), but they solve the “aluminum wear” and “ovalized hole” issue. For a relatively low number of cycles (2,000) and modest loads, it may not be strictly necessary, but it does future-proof the design for abuse or unexpected additional cycles.
4. Practical Recommendations
- Use the unthreaded shank
Make sure the bracket pivots on the smooth shank, not the threads. The diameter of the shank and the hole should be as close as manufacturing allows (e.g., H7/g6 fit or something in that realm) to minimize rattle and wear. - Add Lubrication
At minimum, use a suitable grease or dry lubricant between the bolt and bracket, or between bushing and bolt if you use bushings. This will cut down on wear significantly and also help mitigate corrosion. - Consider a Simple Bushing
If you want a robust design that’s easy to service later, adding a thin-walled bushing (steel, bronze, or oilite) pressed into the bracket is often worthwhile. That way the aluminum is protected. - Use Washers and Proper Torque
Clamp the side plates against the hinge tabs so that the pivot remains on the correct surfaces. Properly torquing the fastener can reduce micromovements that cause fretting in the interface. - Monitor for Wear
With or without bushings, if it’s feasible, keep an eye on hole condition or pivot play over the product’s life.
Conclusion
For only ~2,000 cycles in a typical caravan stabilizer leg, a well-dimensioned, partially threaded bolt can be sufficient—especially if it’s only loaded significantly when static and the pivoting under load is minimal. That said, if you have a strong need to avoid any “looseness” developing or want to ensure easy maintainability, adding a simple sleeve or bushing is a relatively low-cost way to protect the aluminum and maintain tighter tolerances over the long run.
In short: Yes, you can get away with just the bolt in aluminum for low-speed, low-cycle pivots, but a small bushing or sleeve is generally recommended to improve durability and serviceability—particularly if the usage environment is harsh or if tight pivot fit is important.