Spring U-bolts
The spring U-bolts are one of the suspension of a the basic elements of commercial vehicle. They are responsible for the connection of the spring with the axis. Despite of simple construction, they generate a number of problem and doubts. The fitting of the spring to the particular vehicle is one of the most common issues.
How to fit the spring U-bolt to your car?
Fitting spring U-bolts exactly to your car brand. How to do this? The basic is type/form, which should fit by the shape of spring U-bolts bolster.
There are two basic types of U-bolts:
1. Full profile U-bolts,
2. Flattened U-bolts.
In the first group, we can enumerate 3 groups:
1. Straight-bended U-bolts,
2. U-bolts with gentle arch,
3. Round-bended U-bolts (full arch).
The analogous division is concerned with the U-bolts with variable profile.
After the appropriate fitting of the U-bolt type, it is essential to define the diameter of the bar, ofwhich the U-bolt and thread were made.In most cases the thread determine the bar diameter. For example, U-bolts to the BPW axis with M24 thread are made of material with a diameter of Φ24 mm. But, there are also exceptions, for example the U-bolt for Scania 124, has the thread M24, but it is made of the bar of diameter Φ22 mm. That results from the fact that important factor is determining the bar diameter , but we also need to remember about the lead. With the assumption that the particular U-bolt has M20 thread there are three possibilities: M20x1,5; M20x2; M20 (i.e. M20x2,5).
Where:
d – bar diameter
l – thread length
M – thread dimension
After definition of from, bar, and thread diameter we need to set spacing. Giving an external dimension of the yoke is a very common mistake. According to commonly established rules, U-bolts are measured by internal dimensions. The basic spacings range from 60 to 200 mm.
Where:
a – the yoke spacing
The determination of the height of the yoke is the last stage. Similarly like in the case of the spacing the internal dimension is important. From the basic U-bolts the shortest have only 70 mm of height, but the tallest are over 600 mm.
Where:
L – the height of the yoke
The example: U-bolt:BPW C003, 03.138.30.07.4.
Type: Form C- Full profile U-bolt, round-bended U-bolts (full arch).
Bar diameter: Φ22
Thread : M22x80 (given only M22 dimension suggest that this is the standarsthead with the lead of 2,5)
Spacing: 70 mm
Height: 280 mm