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Low pressure disc brakes by MIDIEL Ltd.

The hoist machine brake system consists of the separate brake stands with their own independent hydraulic and electronic control systems, submitting to central controller of the brake system. The pairs of brake elements, independent hydraulic station controlling the brake elements and the local controller of the stand are installed on each brake stand. Such design allows to achieve high compactness, to avoid long connecting pipelines, to increase the brake system speed and reservation degree of the hydraulic system elements.

The elemental base of hydraulic stations and brake elements consists of non-critical, popular hydraulic equipment of common industrial application which has shown its best reliability. The rated working pressure of the brake system is 1.2 MPa (12 kg/cm2). The essential decrease of working pressure of the brake system compared to brake systems of the leading foreign manufacturers allows to reduce the hydraulic system price significantly, to simplify its operation essentially and to raise the safety level.
Features of the brake system The MIDIEL Ltd. work has allowed to develop a compact layout circuit of the brake element with maximal working brake effort of 6.5 t. The experimental sample pair of brake elements was manufactured and tested on the MIDIEL Ltd. stand, and it has shown high characteristics. After that the pre-production models of brake elements were manufactured. The design of brake elements was worked through on these samples. Due to the special design of the brake element, it is not only very sensitive to operating orders, but also extremely simple in operation and setting-up.
The other feature of the brake system is consisting of separate brakes (brake stands), each of which has its own hydraulic and electronic control system submitting to the central controller of brake system. It has allowed to avoid using a complex piping layout and to increase the brake system speed. Besides, this design has led to duplication of all elements of the brake system which allows to avoid standstills of hoist installation at any fallout of the brake system.
At the same the disc brakes control system has been developed. During development of the brake system the primary goal was to maintain high safety, reliability and to achieve high technological level.
Technical characteristics of the MIDIEL Ltd. disc brakes
The brake elements:
Braking effort, kN (ts):
---- Min ______________________________________________ 66 (6.7)
---- Max______________________________________________ 70 (7.1)
Friction factor (rated) ____________________________________ 0.35
Efficiency factor (rated)___________________________________ 0.95
Max specific pressure on friction pads, MPa _____________________ 1.0
Working volume of hydrocylinder at 1 mm motion, sm_______________ 68.7
Oil pressure in the cylinder, MPa (kg/cm2):
---- Rated_____________________________________________ 1.1 (11.0)
---- Max______________________________________________ 1.2 (12.0)
Height of the springs set in free state, mm ______________________ 95.9
Average rigidity of the springs set (rated), kgs/mm_________________ 490
Working liquid _________________________________________ Oil “Turbinnoye 22” GOST32-74
Mass, kg_____________________________________________ 158
Hydraulic brake system:
Rated working volume of the pump, cm ________________________ 32
Rated pressure on the pump output, MPa_______________________ 6.3
Rated frequency of the pump rotation, rpm______________________ 960
Rated supply of the pump, l/min _____________________________ 27.9
Set pressure of the pressure check valve KP1, MPa________________ 2.0±0.05
Set pressure of the pressure check valve KP2, MPa________________ 1.4±0.05
Set pressure of the reduction valve KP1, MPa____________________ 1.2±0.05
Max working volume of the tank, l____________________________ 84
Working temperature, deg. C _______________________________ 10...50
Max dry mass (without oil), kg ______________________________ 415
Operating modes
The disc brakes control system can work in the following operating modes:
• diagnostics,
• adjustment,
• operation, which is also divided into the following modes:
-------- operational manual braking,
-------- operational automatic braking,
-------- locking braking,
-------- auto adjustable safety braking (from the central controller),
-------- safety braking according to the set program (from peripheral controllers of the stands).


Automatic mode (without operator’s participation). Each stand operation is checked: hydraulic and electric parts of brake system, efficiency of each brake element, values of air gaps. All the diagnostics data can be stored.

This mode allows adjusting of the brake system separately on each stand during the hoist operation.
Operational manual braking
This mode provides smooth working braking by the brake handle from the mine hoist desk.
Operational automatic braking
This mode allows automatic fulfillment of some operations of the hoist installation with the help of brake according to the set program.
Locking braking
This mode allows automatic locking of the hoist machine when the drive fulfills the hoist diagram.
Auto adjustable safety braking
In this mode the brake device can work according to different programs. The program is selected during the adjustment depending on the hoist installation features.
Safety braking according to the set program
The safety braking on the separate brake stand is done according to the certain program, in case if it loses communication with the central controller.
The brake system consists of the brake elements installed on the hoist frame. The pairs of brake elements and an independent hydraulic station controlling the brake elements are installed on each brake stand. The brake elements of two stands can be controlled with one hydraulic station (in case if one of the hydraulic stations falls out). Essential features of the brake system are compactness, absence of the long connecting pipelines usual for all disc brake systems, as well as independence of each brake
stand operation and high reservation degree of the hydraulic system elements.
A brake stand with MIDIEL Ltd. disc brakes

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