Hydraulic Disc Brake System

Dongrui Petroleum

In the manual of PS series hydraulic disc brake system, its structure, principle and application

are introduced. Read the manual thoroughly before you operate or repair the disc brake. And install,

use and repair it correctly according to the manual.

The operation effects and service-life of the disc brake system are related with design,

manufacturing, but further lie on proper operation and maintenance of customers. We would like to

supply customers with high quality products in compliance with the quality assurance system of

API, and also hope that the operators can carefully read the manual to give full play to the quality

and the performance of products and successfully achieve the expectant drilling operations. During

product maintenance, it is necessary to use fittings provided by us so that the equipment can realize

its original performance and accidents can be avoided.

Because of the continuous improvements on the products, we decided to carry out the manual

revision，version of the F / 1 to replace version of the F / O,some details in the manual may not be

the same as those in actual. These differences don’t affect the understanding of the product’s

structure, performance and application. As for any questions, please contact with us.

As for the continuous improvements on the drilling technology, you will have new

requirements on the application. We will be very happy to improve our products continuously and

to meet with your special requirements.

Welcome to contact with us.

1 Description

The PS series hydraulic disc brake system which is a product of mechanical-electrical-liquid

integration is the important component of drawworks. To understand and be familiar with its

structure, principle and performance, and do correctly for its maintenance has very important

guidance effect for the drilling rig’s operations on the save side.

The PS series hydraulic disc brake system consists of three parts: brake actuation mechanism,

hydraulic power unit and control system. These three parts are connected through hydraulic pipeline.

The hydraulic power unit is the hydraulic power supply unit, which provides necessary hydraulic

power for the actuation mechanism; the control system is the hydraulic power control unit; the

actuation mechanism is the braking actuation unit, which consists of braking caliper, caliper frame

and friction disc, and the braking calipers include normal service calipers and normal parking

calipers . Friction discs are classified into water cooling, air cooling and solid discs.

This series of brake system has the following four functions:

1. Service Brake

Through operating the handle of the brake valve, adjust the service caliper’s

normal pressure on the friction disc. And thus, provide adjustable braking torque to the rigs to

meet requirements in different working conditions, such as bit feeding, tripping etc.

2. Emergency Brake In case of emergencies, non-operation of drill rig or departure from the

driller’s console, press the Red emergency brake button, the service calipers and parking

calipers will all be applied to realize emergency stop.

3. Parking Brake

When the drilling rig stops working or the driller wants to leave the driller’s

console, pulling down the parking brake handle will realize parking calipers braking to

prevent the hook from sliding.

4. Over-winding Protection

When the hook is lifted to a certain height with load, the service

brake which should be actuated isn’t actuated due to the driller’s failure in operation and some

other reasons, the over winding or colliding prevention valve will give a signal to the service

calipers and parking calipers to realize emergency stop for preventing crown block accident.

2 Main Technical Parameters

3 Working Principle and Structural

Characteristics

The disc brake system mainly consists of three parts, including brake actuating

mechanism, hydraulic power unit and control system.

3.1 Brake Actuating Mechanism

The brake actuating mechanism mainly includes the service calipers, the parking

calipers , the friction discs, and the caliper frame, whose structure is shown in

Figure 1.

3.1.1 Service caliper

The service caliper consists of mainly normal open single-action cylinder, disc

springs, lever and brake pad, the structure of which is as shown in Figure 2.

The principle is as follows: When oil is supplied into the cylinder, theoretical

pushing force F is generated, and F = P ´ A , where A is the area of the piston. the

force F push the piston (13) to stick out,at the same time work on the bottom of the

cylinder(11)to push the cylinder (9) move backward. When the brake pad (1) contacts

the friction disc, force F is transmitted through lever (4) to the brake pads, producing

normal pressure N and the friction force, i.e., the braking force is produced. Due to the

proportional relationship between braking force and oil pressure P, the friction

disc will be braked completely when P reaches a certain value. With the decreasing of

oil pressure P, the braking force will decrease correspondingly. When oil pressure P=0,

the lever returns to its original position acted by reset spring (10), causing the brake

pad to be released from the friction disc, and consequently, the service caliper comes

into completely released condition.

3.1.2 Parking Caliper

The parking caliper consists of normal closed single-acting oil cylinder, disc

spring, lever and brake pad, seeing Figure 3.

The principle of the parking caliper is just opposite to that of the service caliper.

When the normal closed single-acting cylinder’s oil pressure is P=0, the set-in disc

springs transmits the force through the two levers to the brake pad and consequently

acts on the friction disc, producing normal pressure N and then realizing brake. When

the oil pressure of the cylinder P is not equal to 0, which means oil pressure exists, the

oil pressure will overcome the disc spring force to compress the disc spring, releasing

the brake through the lever.

3.1.3 Friction disc

The friction disc, which forms the brake pair together with brake pad, is one of

the core components. Usually, each set of product is equipped with two friction discs,

which are mounted on both ends of the drawworks drum.Some smaller types only

equip with one friction disc，which is mounted on one ends of the drawworks drums.

According to structures, friction discs are classified into three types: water

cooling, air cooling and solid discs.

● The water-cooling disc has cooling water channels inside, and it has water inlet

and outlet ports at the inner diameter of the friction disc, and water draining port at

the outer diameter for draining all water in channels to prevent the friction disc

from being frozen and broken in cold weather. During normal operation, the water

draining port is sealed with a screw plug. When the braking system is working,

cooling circulation water is fed to the friction disc to balance the heat produced by

friction of the brake pair.

● The air-cooling disc internally has natural ventilation channels to discharge heat

through natural ventilation channels and surface.

● The solid disc discharges heat through the surface. Such type of friction disc is

mainly used for smaller drilling rigs.

! Cautions !

During normal operation of drilling machine, water-cooled

brake must provide circulating water to brake disc. When drilling

machine does not work in winter, cooling water in brake disc must be

drained to avoid freezing inside to crack the disc.

3.1.4 Caliper frame

The caliper frame is the base of the actuating mechanism. The service caliper and

the parking caliper are mounted on this base.

3.2 Hydraulic power unit

The hydraulic power unit includes oil tank assembly, pumps, control block

assembly, oil filling assembly and electrical control box, the hydraulic power unit

structure is shown in figure 5. And its operating principle is shown in Figure 4

Figure5 Hydraulic Power Unit Structure

3.2.1 Oil tank Assembly

The oil tank assembly includes oil tank, oil suction valve, oil draining valve, oil

level/temperature gauges and cooler,they are shown in figure 6 . The oil suction valve

is used to separate the oil tank from suction port of the pump by closing the valve

when the oil pump is maintained or repaired. During normal condition, this valve is

open.

Figure 6 Oil tank assembly of hydraulic power unit

The function of Oil return valve is to close the valve in the maintenance, So that

the Oil tank and the another pump disconnect, to prevent leakage of hydraulic oil. In

normal working hours, it is turned.

The oil draining valve is provided for hydraulic oil replacement., it is closed.

Oil level/temperature gauge is provided for checking oil level and temperature in

the oil tank.

The cooler is of tube-row type, which is used to balance heat produced in the

whole system.

The water cooler or air cooler is used to balance the temperature of the system. it

must be used When the temperature of the hydraulic system above

60 ℃

3.2.2 Pump Groups

The pump is the heart of the hydraulic system. Two same

plunger pumps are provided in the hydraulic system. Both pumps

are driven by an explosion-proof motor. One pump is in operation while the other

stands by, alternatively in operation. It is shown in figure 7.

Figure 7 pump motor group

3.2.3 Control Block Assembly

The control block assembly mainly consists of oil way block,

accumulator, shut-off valve, one-way valve, relief valve and high-pressure filter. It is

shown in figure 8.

The accumulator can reduce pressure impulse in the hydraulic loop and provide certain reserved energy when the pump can not work normally, and make working calipers braking 4~6 times normally in about 10 min.

The shut-off valve is used to “dump” the pressure in the accumulator. In normal

operation, tighten the shut-off valve securely, or else, the pressure of system can’t

be established.

The function of the one-way valve is to separate the oil discharge ports of the two

pumps to form three oil loops, which are independent from each other and

also connected with each other, and to prevent oil from flowing back in the

accumulator.

The safety valve is an overflow valve, which is used for protection.

The high-pressure filter is used to filter high-pressure oil to guarantee

cleanness of the hydraulic system.

3.2.4 Oil Filling Assembly

The oil filling assembly consists of one hand-operated pump

and a filter. Shown in figure 9 .Oil is filled into the tank through

the hand-operated pump to guarantee cleanness of the oil.

3.2.5 Electrical Control Cabinet

The electrical control cabinet of the hydraulic power unit is mainly used to control

the start and stop of the motors and heater in the system. The electrical control cabinet

is explosion-insulated. The working principle is shown in Figures 10.

3.3 Control system

The control system includes braking valve assembly, parking brake valve

assembly, control valve group, pipes and pressure meters. The hydraulic principle is

shown in Figure 4.

3.4 Working Principle

Service Brake: Service brake is realized by means of brake valve (9), which is

controlled by the brake handle. The brake valve is a hand-operated proportional relief

valve, the output pressure of which changes proportionally with the pulling of the

brake handle. When the brake handle is pulled to the Max. angle, the corresponding

output pressure of the valve has its largest value, and the service caliper’s braking force

reaches the largest value; when the brake handle is pushed to its original position, the

output pressure of the valve is zero, and the service caliper is released.

Parking Brake: The parking brake valve (13) is a hand-operated reversing valve.

When the handle is pulled, the parking brake valve will change the direction to relief

the pressure in the parking caliper’s oil cylinder and thus the spring force will make the

parking caliper realize parking brake.

When the parking brake needs to be released, first, pull the handle of brake valve

to “brake” position

so that the brake valve (9) controls the mis-operation protection valve (10) to change

direction. Then, push the handle of the parking brake valve to feed hydraulic oil into

parking caliper’s cylinder to overcome disc

spring’s force so that parking brake is released.

! Cautions !

When parking brake needs releasing, the service brake handle must be

pulled first to confirm that the service calipe are in the working braking state，

and then the handle of the parking brake should be pushed to release the parking

brake. Otherwise,There will be free fall of the car , and property losses, injuries

or even death will be induced!

Emergency Brake: Emergency brake is controlled by emergency brake valve

(11), which is a manual reversing valve and controls pneumatic reversing valve (12).

When the emergency brake button is pressed, air supply is cut-off and the pneumatic

reversing valve (12) is reset by the spring to make the parking caliper brake. At the

same time, hydraulic reversing valve (14) changes direction due to loss of pressure at

the controlling end to let hydraulic oil flow directly into the working cylinder to make

the service caliper brake, which means that all calipers brake and emergency brake is

released.

! Cautions !

When emergency brake needs releasing, which is just like release of

parking brake, the brake handle should be first pulled to “braking” position, and

then emergency brake button should be pulled out. If not, drilling strings will

drop freely, and property losses, injuries or even death will be induced!

Overwind/anti-collision protection: When the hook elevates to the set position

and the braking of work can not be executed due to misoperation or other reasons, the

over-wind device installed on the winch (or the anti-collision device installed near the

overhead crane) will activate by a collision from an external force and cut the air

source to the pan brake control system. The pan brake control system can immediately

realize the emergent braking so as to prevent the collision accident of overhead crane.

Each anti-collision system should be periodically checked and debugged for normal

operation so that the drill rig could work safely and reliably. After the collision, pull

the brake crank to “brake” position and then make unlock operation; otherwise, the

drilling tool will descend freely, bringing about property damage, personal injury

and even death!

Mis-operation Protection : To release parking brake, the braking lever must be

first pulled to “braking” position, then the parking handle is pushed Or press the

emergency brake button to release parking brake to guarantee safety. If the driller

operates without following regulations, instead of first pulling the braking lever, but

pushing the parking handle Or press the emergency brake button first, now, not only

the parking brake is not released but also the service caliper is under full braking

condition, thus to realize mis-operation protection. Thus the driller is forced to operate

according to regulations.

Cautions:The shortcoming of the misoperation protection function is: in the

normal operation process, it is easy to cause the misunderstanding of the driller. If

the misoperation protection function is realized, the driller must move the

parking handle or the emergency brake button to the brake position, and then

According to the operating procedures, the operation is unlocked, otherwise it is

easy to cause an accident.

4 Installation

4.1 Install the Friction Disc

4.1.1 The stagger of the working surface of the friction disc to the end surface of rotary drum shaft

should be less than 0.3mm.

4.1.2 The friction disc should be cleaned, with the friction surface free of oil and dirt.

4.1.3 For water-cooled friction disc, water inlet and outlet pipes should be connected.

4.2 Install the Brake Calipers and Caliper frames

4.2.1 Fasten the upper and lower transit plates firmly onto the caliper frames.

4.2.2 Install the brake calipers on the caliper frames. On completion of installation, turn them to see

whether they rotate flexibly, whether there is blockage or jam, and whether it is difficult to rotate. When the

parking calipers are installed,

adjusting nut should be rotated so that the interval between two brake pads becomes the maximum for

installation of caliper body.

4.2.3 Install the whole actuating mechanism onto the drawworks.

Requirements of Installation:

1. Must fasten the upper and lower transit plates firmly onto the caliper frames.

2. The gap between the outer circle of the friction disc and inner circle of the caliper frame should be

uniform; no interference with the caliper frame is permitted.

3. The caliper frame should be parallel and centered with the friction disc, with allowable

deviation ±1mm .

4. The brake pads should be enclosed within the friction disc.

5. After adjustment and alignment, weld the upper and lower transit plates to the designed location on

the drawworks base.

! Cautions !

The brake disc and caliper must be installed strictly in accordance with the

descriptions, otherwise, eccentric wear of brake block and brake disc will occur, which

may result in the disfunction of control, property damage, personal injury and even

death if serious.

4.3 Install the Hydraulic power unit and Control system

Install the hydraulic power unit and control system on the designed location.

4.4 Connect the Hydraulic Piping

The hydraulic piping mainly consists of high-pressure hoses, quick couplings and pipe clamps.

The connection of hydraulic piping includes connecting hydraulic power unit, drilling control panel

and braking actuation mechanism with high-pressure hoses according to design requirements to form a

complete hydraulic system. If disconnection and moving are required, quick couplings are provided for easy

and quick disconnection and prevention of contamination of hydraulic pipe. In case of dismantlement, pull

out the rapidly pulled connector for pipeline and cover the protective cap for prevention of pollution of

hydraulic pipes.

The connections of the three major units are shown in Figure 14.

! Cautions !

1. It is strictly forbidden for the nonprofessional personnel to randomly dismantle the

pipelines and hydraulic valves, replace the pipeline joint, exchange the pipelines or

interchange the different types of hydraulic valves. The abnormal operation may

most probably result in big safety accidents and even personal injury or death.

2. The rapidly pulled connectors on the outputs of parking caliper and working

caliper for the manifold blocks of hydraulic station and operating console must be

exchanged in reverse directions. The pipeline of parking caliper shall use the red