# ZM1\-01 Assembly Guide

Assemble the ZM1\-01 cross\-arm of a 110 kV transmission tower, panel by panel

By Sheng Li

Topic: Home & DIY

[Open the interactive Jig](https://ask.jig.com/j/DCQCS15YBUnh)

## Guide

### 1. ZM1\-01 Cross\-Arm

This steel frame becomes the top arm of a 110 kV power\-line tower\. It holds the middle wire underneath, and two little peaks carry the ground wire that guards the line from lightning\. All its pieces are laid out in the yard\. Tap any piece to see its name\.

Finished, it is 5\.39 m long and weighs about 1,050 kg, so a crane lifts each panel\.

### 2. 1 · Set the Bottom Chords

Lower the two long bottom chords onto the timber blocks, 0\.8 m apart\. A chord is a main rail of the frame\. These are L\-shaped steel angles, 63 mm on each side\.

### 3. 2 · Fit the Lower Bracing

Lay the criss\-cross lower bracing onto the chords, with the centre crossbeam in the middle\. Triangles cannot squash out of shape, so the X pattern keeps the frame rigid\.

### 4. 3 · Stand the Cross Frames

Stand the five cross frames on the lower plane: one at each end, one in the middle and one 1\.9 m to each side\. They set the square shape of the box\.

### 5. 4 · Hang the Side Faces

Lower the two side faces of X bracing just inside the chords\. Where two braces cross, a small packing plate fills the gap so they can be bolted together\.

### 6. 5 · Close the Top

Lower the top plane, with its two top chords and bracing, onto the frames\. The box is now closed, 0\.75 m deep\.

### 7. 6 · Raise the Ground\-Wire Peaks

Set a peak on each end of the arm\. Each one rises to 1\.8 m above the bottom chords\. The ground wire hangs from the small hole at the tip of its arm\.

### 8. 7 · Slide On the Hanger Plates

Slide the two hanger plates onto the plate under the centre, one on each side\. The middle power wire will hang from their three lower holes\.

### 9. 8 · Fit the First Bolt

Push an M20 bolt through both hanger plates into the nut behind\. Then tighten it with the spanner until it is snug\.

M20 means the bolt is 20 mm thick\.

### 10. 9 · Fit the Other Three Bolts

Fit and tighten the other three bolts the same way, so all four holes are filled\.

### 11. Done

The cross\-arm is ready to be lifted onto the tower\. On the real arm, crews fit more than 900 bolts like these\.