GB1581381A

GB1581381A - Brakes for winding machinery

Info

Publication number: GB1581381A
Application number: GB528477A
Authority: GB
Original assignee: Wild & Co Ltd M B
Current assignee: Wild & Co Ltd M B
Priority date: 1978-05-09
Filing date: 1978-05-09
Publication date: 1980-12-10

Description

(54) BRAKES FOR WINDING MACHINERY (71) We, M.B. WILD & COMPANY LIMITED, a British company of Wharton Street, Birmingham B7 5TS, England, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to winding engines used for raising and lowering cages in mine shafts and especially those used for conveying men. In particular, the invention is concerned with the brake systems used for such machinery and concerns the ability to provide efficient braking even in the event of some fault developing.

It is now a requirement, at least in Great Britain, that dual brakes should be used for braking the drum on which the cable is wound. There are a number of different types of braking systems in use and there are some which have force applying means such as springs which apply the braking force and hydraulic pressure is applied to release them. The springs react against some fixed restraint. In known systems the springs are independent for each brake, even though there may be a common operator control for applying the brakes together. With such arrangements the failure of only one of the brakes results in the braking force applied being half that existing when both brakes are working normally. Of course in such a failure situation, the effective braking force applied to the drum is also, therefore, halved.

It is the object of this invention to provide brake apparatus for a winding engine, having dual brakes, in which the braking force is not halved if one of the brakes fails to operate.

According to the invention brake apparatus for a winding engine comprises dual brakes, which are operated by respective force applying means reacting against a single back up system, the force applying means acting against the said back up system through respective linkages which are common at their connections with said back up system.

Preferably, each of the force applying means is in the form of a spring system and these are arranged to react against the single common back up system which is in the form of a weight.

In this arrangement the weight can apply full force to react against the two spring systems. In the event that one of the brakes fails. to operate, for instance, in the event of breakage of part of its linkage, the weight will apply only to the other brake, but the force which will be available at that one brake will be that normally available for both the brakes. Thus, the braking effort applied to one of the brakes, in the event of failure of the other of the brakes, will be substantially that normally applied to both brakes.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a brake system constructed in accordance with the invention; Figure 2 is a partial end view on line II-II in Figure 1, and Figure 3 is a representation of the associated hydraulic system.

Figure 1 illustrates one of a pair of brakes for the winding drum (not shown) of a winding engine for raising and lowering a cage in a mine shaft. The brakes are situated at opposite sides of the drum and each comprises a pair of shoe members 10, 11 carrying respective brake linings 12, 13. The shoe linings engage on respective cylindrical zones on the drum. The members 10, 11 are pivotally mounted upon a fixed base 14 and each pair are arranged to move towards and away from each other for actuation and release of the brakes. To actuate the brakes, the members are connected by an adjustable link 15 pivotally mounted at one end to the member 11 while the other end is pivotally connected to a triangular plate 16. One corner of such triangular plate is connected to the link 15 and an adjacent corner is pivotally connected to the member 10. The third corner of the triangular plate is connected to a main operating rod 18. This rod 18 is connected to the piston of a piston and cylinder unit 22. The rod 18 carries a spring bank 24 enclosed by a support cage 20 which includes tie rods, a plate and an abutment 20a for the spring bank 24. The spring bank 24 comprises a stack of disc springs surrounding the rod 18 and acting between the abutment 20a and an abutment 18a fixed to the rod 18 outside the cylinder of the unit 22. The tie rods of the support cage are adjustable in length and, when tightened, precompress the spring bank 24. The cylinder of the unit 22 is fixed to a part on the plate of the support cage 20.

Hydraulic fluid may enter the cylinder of the unit 22, as will be described, at the side of the piston remote from the spring bank to provide hydraulic force for still further compressing the spring bank until it becomes, in effect, solid and inoperative as a spring.

The spring support cage 20 to which the cylinder of the unit 22 is fixed, is connected through a rod 25 to a crank lever system common to both brakes which comprise a rotatable shaft 26 having fixed at its ends respective short levers 27 connected to the spring support 20 by the rod 25. Connection is through a pivot 23. The shaft 26 is mounted near its ends, in respective bearings 28, 29 and in its mid section in bearings 30, 31.

The mid section of the shaft 26 carries further fixed levers including a single central long lever 32 and two flanking shorter stop levers 33, 34 extending away from the longer lever 32 and having at their outer end, abutment surfaces 35 which can engage respective adjustable abutments 36 (only one being shown), these being provided on fixed structure 37 on which the shaft bearings are also mounted.

The end of the long lever is connected to a part 38 carrying a set of weights 39. Also connected to the long lever 32 is a hydraulic piston and cylinder unit 40, the other end of which is connected to a fixture 41. In normal operation the brakes are held in the released position by application of hydraulic fluid to the pistons of the two units 22 thus overcompressing the spring banks 24. This is accompanied by pressurisation of the cylinder 40 which holds the weights. Normal manual brake operation involves release of the pressure from the piston and cylinder units 22, and 40, whereupon, the spring banks 24 draw the rods 18 downwardly thus actuating the brakes.

Variable brake actuation is available by governing the pressure in the piston and cylinder units 22 and 40. The pressure applied during use to the cylinder 40 is sufficient to bring this to the maximum of its permitted travel. This coincides with a position for each lever 33 just clear of the appropriate abutment 36. During normal operation the piston of the unit 40 does not move at all in its cylinder. As will be explained, however, small movement of the levers is permitted but the set of weights 39 normally occupies the fully raised position.

In the event of emergency braking being required however, all the piston and cylinder units are exhausted of hydraulic fluid in a manner to be described. The spring banks 24 cause rapid actuation of the brakes and the reaction of this is felt upon the set of weights 39 which is of a size sufficient to counterbalance the force of the two banks 24 together. In practice, however, the set of weights is a little larger than is required exactly to balance the spring forces. The small movement which can take place is therefore used not only for ensuring that the components will move when required, but also for monitoring purposes.

The apparatus also provides substantially full braking effort being applied in the event of failure. If one of the brakes fails to operate for instance, because the main rod 18 has broken, one side of the system will therefore be completely inoperative. When the brakes are applied, the remaining brake has a reaction force equal to half that normally available due to the set of weights 39. Consequently, substantially full braking effort is applied on the remaining brake. If however, the set of weights 39 should fall off, reliance would be placed on the two spring banks 24 but the reaction against which these act would be provided by the unit 40 and if this should fail by the two abutment surfaces 35 which again would provide full reaction and thus full braking effort.

In Figure 3 the two cylinder units 22 and the cylinder unit 40 are shown at the top.

There is shown a manual control lever 42 which is the normal manual control for brake actuation.

The hydraulic system includes a reservoir 50 having a level gauge 51, a temperature gauge 52, a visual level gauage and breather assembly 53 and a thermostat 54.

The supply of hydraulic fluid from the reservoir 50 to the cylinders 22 and 40 takes place through a supply system including two pumps 55, 56 driven by respective motors 57, 58 and connected in dual supply lines 59, 60 and joining to feed a common supply line 61. The common supply line 61 branches through non-return valves 62, 63, used during testing of the system, to the cylinders 22 and 40 which are interconnected through a line 64.

The common supply line 61 includes pressure switches 65, 66, 67 connected in respective parts of the system and a pressure gauge 68. An accumulator system is also provided in the line 61. This includes two hydraulic accumulators 69, a non return valve 71 and a flow control valve 72 for use in the event that the accumulators are required to provide pressure in the system.

The line 61 contains a further non-return valve 70 upstream of which is a connection to the tank through a brake lock valve 74 used to ensure that the brakes cannot be released, if this condition should be required. This valve is electrically operable. In parallel with this is another valve 75 used during maintenance, for the same purpose.

Bypassing the pumps 55, 56 is a line containing a hand pump 73.

Top-up supply for the reservoir 50 is obtained from a source indicated generally at 76.

To actuate the piston and cylinder units 22 and 40 there are respective main valves 77, 78. These are normally controlled through a pilot system shown in dotted lines. This has the manual control lever 42 which actuates a valve 79 to allow the valves 77, 78 to open, thus exhausting the fluid from the main supply to the reservoir 50, this takes place through respective lines 80, 81.

There are two further portions of the pilot system indicated generally at 82 and 83 which represent emergency systems and contain valves 84, 85 with associated pressure level or backing pressure valves. The valves 84, 85 are actuated through electrical signals in the emergency solenoid systems of the safety circuit associated with the brakes.

These are separated, as are the main valves 77, 78, by non-return valves 86, 87 disposed at either side of the connection from the manual control valve 79.

Connecting with the two lines 80, 81 containing the main valve 77, 78 respectively are two lines 88a, 88b containing respective valve 89, 90 and providing supply to two hydraulic accumulators 91, 92 respectively.

These contain gas containers of variable volume which are connected to a differential signal gauge 96 to provide a visual reading of the relative pressures in the two halves of the system, comprising the two lines 80 and 81. The lines 88a, 88b are connected in the lines 80, 81 between the valves 77, 78 and the units 22 and 40 since only when the valves 77, 78 are closed does pressure exist in the system. Respective non-return valves 86, 87 in the pilot system and 93, 94 in the lines 80, 81 are provided to prevent any residual pressure on one side leaking through to the other side. Only if different pressures exist, indicating a fault, will a positive reading be obtained on the gauge 96.

In normal use the brakes are held in their released positions by application of pressure in the units 22 and 40.

For normal brake operation the main valve 77, 78 remain open as does the manual valve 79 controlled by the manual control lever 42. To apply the brakes, it is necessary to exhaust the pressure in the units 22 and also of course 40. This is accomplished by manual opening of the manual control valve 79 which allows exhaust of pressure through the return line 95 to the reservoir 50. The pressure normally in the pilot system and thus also that in the main valves 77, 78 falls, allowing these valves 77, 78 also to open, thus exhausing through the lines 80 and 81 respectively. This results in fall in the pressure in the piston and cylinder units 22 and 40 thus allowing the spring banks to swing the triangular plates 16, which in turn cause the brake linings to grip the drum.

In the event that the brake system develops a fault the apparatus is designed so that the brakes will be applied. Any hydraulic fault will result in fall in the pressure in the units 22 and 40 thus allowing the brakes to operate automatically.

If the emergency conditions is such that a trip occurs, that is in the event of the abnormal but not absolute failure, the valves 84, 85 are actuated. This causes the pilot system pressure to fall thus in turn actuating main valves 77, 78 to operate to relieve pressure in the system and thus exhausting the units 22 and 40 so that the brakes operate. A circumstance in which this trip condition exists is in the event of excessive speed of travel of the winding drum and thus of the cage on the cable wound on the drum.

Mechanical failure of one of the linkages results in the weights applying the force normally available for actuating both brakes, to be applied to the remaining operative brake so that the braking effort applied to the drum is substantially the same as when two brakes are operating normally.

If lever 32 breaks, the stop levers 33, 34 to engage their abutment surfaces 36 which then provide the reaction against which the spring bank force acts. Should the weights become detached the piston and cylinder unit 40 is designed to be at the end of its travel so that it will normally accept the load in the event that the weights become detached.

Provision is made for wear on the linings of the brakes. As wear takes place the springs produce less force, but this is coun terbalanced by downward movement of the weights. When the long lever 32 reaches a predetermined position it will actuate a switch 97 which provides an electrical signal.

Adjustment to compensate for the wear is by adjusting the rods 15 between the members 10 and 11.

WHAT WE CLAIM IS: 1. Brake apparatus for a winding engine comprising dual brakes which are operated by respective force applying means reacting against a single back-up system, the force applying means acting against the said backup system through respective linkages which are common at their connections with said back-up system.

2. Brake apparatus as claimed in claim 1 in which the single back-up system includes a set of weights connected through a common linkage to respective brake actuating linkages.

3. Brake apparatus as claimed in claim 2 in which the common linkage includes a rotatable shaft connected to the set of weights and to the two brake actuating linkages respectively.

4. Brake apparatus as claimed in either of claims 2 and 3 in which the brake actuating linkages include respective brake operating spring banks operable in a sense to apply the brakes and having associated hydraulic units arranged when under pressure to act against the spring banks to hold the brakes in released condition.

5. A brake apparatus as claimed in any one of claims 2, 3 and 4 in which the set of weights is supportable from a hydraulic unit arranged to exhaust in the event of emergency brake actuation.

6. A brake apparatus as claimed in either of claims 4 and 5 in which hydraulic control of the hydraulic units is through a circuit including main exhaust valves operable manually or in emergency without manual control to exhaust the cylinder units to permit brake application.

7. Brake apparatus as claimed in claim 6 in which the hydraulic system includes dual supply pumps and means preventing pressurisation of one part of the circuit associated with one of the hydraulic units when the other is unpressurised.

8. Brake apparatus as claimed in either of claims 6 and 7 in which the hydraulic system includes safety switches arranged to prevent supply of hydraulic fluid under pressure to the hydraulic units to allow brake application.

9. Brake apparatus for a winding engine comprising dual brakes substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. terbalanced by downward movement of the weights. When the long lever 32 reaches a predetermined position it will actuate a switch 97 which provides an electrical signal. Adjustment to compensate for the wear is by adjusting the rods 15 between the members 10 and 11. WHAT WE CLAIM IS:

1. Brake apparatus for a winding engine comprising dual brakes which are operated by respective force applying means reacting against a single back-up system, the force applying means acting against the said backup system through respective linkages which are common at their connections with said back-up system.