03/01/2020.

Gripping trolleys

In addition to the trolley itself, the parts that make it up are the grippers, and their articulation, which has two axles. One, longitudinal, the pinch axis, allows the grippers to spread then to grab a semi-trailer or a swap body; the other, perpendicular, the lifting axle, allows the grippers to be placed in the working position or in the rest position when working with containers and twist locks.

I wondered for a moment whether to make these articulations functional. To do so implied an increased risk of weakness. Not to do so led to designing two different parts: one representing a trolley with grippers at work, the other with grippers at rest. I opted for the first solution.

Installation of photo-etched accessories

These accessories are generally small and practically require using a magnifying glass. First the gripper’s stand. A notch is provided in the 3D part. CA gluing.

Gluing a stand on a gripper

Then, the stand rest and the trolley’s third support. These parts are positioned using pins on the trolley. You can see that the trolley is poorly cleaned. While looking at this photo, I realized this problem. I had to dismantle the accessories already in place to do the cleaning again. Fortunately, CA glue is easily dissolved by acetone.

Gluing a stand rest

Gluing the trolley’s third support

Assembly of the articulation axles

The problem here is twofold: the axles should enter their housing without forcing too much (risk of breaking the resin), but, at the same time, the articulation should not have too much clearance, to allow the grippers to be positioned at one’s will.

The solution that I found is to adjust the hole diameter with a carbide drill bit, to the exact axle diameter, here 0.8 mm, by hand, very slowly and without insisting: I stop the rotation just before getting through.

Bore of an axle hole

Click the picture to zoom.

To insert the axle, quite short (4.5 mm), I place it in a hand-held drill…

Installation of an articulation axle

… Then I push it in carefully before releasing hand-held drill and finishing the positioning.

Installation of an articulation axle (continued)

As a result, the grippers hold in the air by themselves.

Trolley completed: grippers hold in the air

Some tests on the older spreader

Grippers at rest.

Grippers at rest

Grippers at work.

Grippers at work

Grippers at rest, detail.

Grippers at rest, detail

Grippers at work, detail.

Grippers at work, detail

Et voilà, it remains only the decoration, painting and installation of decals. But this is another story.