Cutter Bits

Hydraulic Nuts

The Hydraulic Nut is a permanent fixture, replacing the conventional nut and retaining the high bolt load and extension in small space envelopes where there may not be sufficient space to use tensioners. The nut can be retrofitted to existing plant and is a simple and accurate solution to mechanical jointing problems.

WHY USE HYDRAULIC NUTS?

Consistent

Using multiple Hydraulic Nuts on a bolted joint gives a much improved uniform bolt load across all bolts.

Axial Bolt Load

Bolt load is applied axially to the bolt. Inconsistencies such as friction, bending and lubricant are not a factor when using Hydraulic Nuts. No torsional stresses are involved.

Fast Tensioning

Multiple Hydraulic Nuts offer a quick and accurate method of tightening a bolted joint.

Accurate

Bolt load is directly proportional to the pressure applied to the Hydraulic Nut.

The Hydraulic Nut is a permanent fixture, replacing the conventional nut and retaining the high bolt load and extension in small space envelopes where there may not be sufficient space to use tensioners. The nut can be retrofitted to existing plant and is a simple and accurate solution to mechanical jointing problems.

The locking for hydraulic nuts is different from common nuts. When the hydraulic nut is locking, it causes ultra-high pre-tightening force by hydraulic pressure (about 200 MPa), which can get close to the yield point of the bolts. It will not loosen even if it is in vibrating condition.

Hydraulic nut is especially suitable in the fastening for the coal miners and roadheaders in underground mining where the space is very narrow. It can also be used in the machines for metallurgy , chemical industry and engineering machinery.

Working principle of hydraulic nuts :

Hydraulic nut is a kind of locking device which relies on pre-tightening force that can make the connecting nuts longer. So the high-strength two head nuts above 10.9 grade must be used.

Schematic diagram ( picture 1). Firstly, the hydraulic nut pre-tightens, ulltrahigh pressure manual pump injects the high pressure oil to the cylinder block of hydraulic nuts by ultrahigh pressure hosepipe which will make the bolt longer.
There will be a gap between the back bolt and the cylinder(picture 2-2), now turn the back bolt so that it will get very close to the cylinder(picture 2-3), and then tighten the back bolt.

Forcing system of hydraulic nuts :

The forcing system of hydraulic nuts are mainly made up of ultra high-pressure Manual oil pump, ultrahigh pressure flexible pipe, hydraulic nuts and high-strength bolt (picture 3)

1.ultrahigh pressure manual oil pump

Ultrahigh pressure manual oil pump is a power equipment which offers hydraulic nut high pressure oil, it is mainly made up of plunger pump, oil storage tank, ultrahigh pressure gauge, high-pressure unloading valve, low-pressure unloading valve, oil filter.

2. Ultra-high pressure flexible pipe

It is made up of ultra high-pressure hosepipe, filter joint, quick coupling.

3. The connection of hydraulic nuts and ultrahigh pressure hosepipe

It connects very quickly by quick joint and filter joint, it is very convenient in operating and moving.

No. Code name M Model Overall dimensionsΦB×A Route
1 KMYE M24×2 Φ62×50 5
2 FMYE M24×3(Reverse installation) Φ62×52 5
3 KMYGA M27×3 Φ68×50 5.5
4 KMYGB M27×2 Φ68×50 5.5
5 KMYA M30×3.5 Φ68×50 5.5
6 KMYB M30×3 Φ68×50 5.5
7 KMYBI M30×2 Φ68×50 5.5
8 KMYH M33×3.5 Φ82.5×64.5 5.5
9 KMYD M36×3 Φ82.5×64.5 14
10 KMYF M42×3 Φ84×61 10
11 KMYC M42×3(Major external diameter) Φ94×66 14
12 KMYI M48×3 Φ106×67.5 14
13 KMYJ M52×3 Φ106×67.5 14
14 KMYK M64×4 Φ125×82 14
15 KMYR M95×2 Φ195×132.5 14
16 FMYQ M110×2 Φ215×153 14
17 KMYA M30×3.5(Reverse installation) Φ68×49.2 14
18 KMYKA M56×4 Φ125×82 14
19 FMYK M64×4 Φ125×110 14