Overview
Drive belt, 5VX433, EPDM. Sapphire part number 37-070, listed in the parts schedule as Belt, 5VX433 EPDM.
Reading the belt code
The code is the specification, and it is worth being able to read it:
- 5V — the narrow-wedge V-belt section
- X — cogged (notched), which lets the belt run round smaller pulleys and shed heat better than a plain belt
- 433 — the length, in tenths of an inch, so 43.3 inches
Sapphire list several belts in the same family — 5VX412 (37-066) and 5VX510 (37-107) among them. A belt of the right section and the wrong length will fit onto the pulleys and will not tension correctly. Read the code off the old belt.
Why EPDM
EPDM belts run cooler and last longer than older neoprene constructions, and they resist the heat cycling a truckmount engine bay puts a belt through. They also do not develop the same cracking with age.
The practical consequence is that an EPDM belt does not warn you the way an old-style belt did. A neoprene belt cracks visibly as it approaches the end of its life; an EPDM belt wears in the sidewalls and sits deeper in the groove instead. Judge an EPDM belt by how it sits in the pulley, not by looking for cracks. If it is riding low in the groove or touching the bottom, it is finished.
Fitting advice
Set tension to the engine or machine manufacturer's specification, not by feel. Over-tension destroys pump and blower bearings — that is the expensive failure, and it is silent until the bearing goes. Under-tension glazes the belt and polishes the pulley, after which no belt will grip properly.
Check pulley alignment while the belt is off. A belt that has worn unevenly, or that has thrown black dust into one side of the machine, is telling you the pulleys are not in line and a new belt will do the same.
Inspect the pulley grooves. A glazed or worn groove will not drive a new belt.
Re-check tension after the first few hours — new belts bed in and lose tension.
Frequently asked questions
What length is it?
43.3 inches, from the 5VX433 code.
Which machines take it?
Sapphire list it in their parts schedule without naming a machine. Send us your model and serial number and we will check, or read the code off the belt you are replacing.
Can I fit a plain 5V belt instead of a cogged one?
Not on a drive specified for a cogged belt. The cogging is there because the pulleys are small enough to need it.
How often should it be replaced?
On condition, and always if it is riding low in the groove or has been running out of alignment.
Read the code off your existing belt and send it to us with the machine model — we will confirm the right belt before you order.
