Faq

Multi-turn gearboxes also called bevel gearbox,bevel gear operator ,bevel gear actuator according to different countries languages.Multi turn gearboxes is part for operation for Gate Valve, Globe Valve,Knife gate valves such multiple turn valves and dampers,isolation dampers in industries such as HVAC,Power ,

Chemical and Water and Waste.

Part-turn Gearboxes also called 1/4 worm gearbox.Part-turn gearboxes is intended for the operation of ball valve, plug valve and butterfly valve as well as power and process dampers.

The difference between Multi-turn Gearbox and Part-turn Gearbox:

1. Used for different valves:

Multi-turn gearboxes for assembly on Gate valve, Globe Valve, isolation dampers.

Part-turn gearboxes for assembly on Ball valve, plug valve, butterfly valve

2. Worm

Multi-turn gearbox: The part of worm is whole worm.

Part-turn gearboxes: The part of worm is mostly 1/4 worm, but sometimes also whole worm of special projects.

3.Bore and Output sleeve

Multi-turn gearbox: Mostly of bore part is removable output sleeve to facilitate spindle machining by customers.

Part-turn gearbox: Bore with key mostly without removable and machined by part-turn gearbox supplier of HUNAN TB VALVE CO.,LTD

IP Grade also called IP Ratings(Ingress protection).with two digit number established by the International Electric

Tech Commission,is used to provide an Ingress Protection rating to a piece of electronic equipment or to an enclosure

for electronic equipment.The protection class after EN60529 are indicated by short symbols that consist of the two code letters                     IP and a code numberal for the amount for the protection.

Example:IP68

The first digit of 6 represent protection against ingress of solid objects.

The second digit 8 represent protection against ingress of liquids.

Ip                       IP First Number-Protection against solid objects

0.No special protection

1 .Protected against solid objects up to 50 mm, e.g. accidental touch by persons hands.

2 .Protected against solid objects up to 12 mm, e.g. persons fingers.

3.Protected against solid objects over 2.5 mm (tools and wires).

4.Protected against solid objects over 1 mm (tools, wires, and small wires).

5.Protected against dust limited ingress (no harmful deposit).

6.Totally protected against dust.

IP Second number – Protection against liquids

0.No protection.

1.Protection against vertically falling drops of water e.g. condensation.

2.Protection against direct sprays of water up to 15o from the vertical.

3.Protected against direct sprays of water up to 60o from the vertical.

4.Protection against water sprayed from all directions – limited ingress permitted.

5.Protected against low pressure jets of water from all directions – limited ingress.

6.Protected against temporary flooding of water, e.g. for use on ship decks – limited ingress permitted.

7.Protected against the effect of immersion between 15 cm and 1 m.

8.Protects against long periods of immersion under pressure.

Referenced from: https://www.mpl.ch/info/IPratings.html

Basic Formulas

MA(Mechanical Advantage)=Output torque/Input torque

Overall mechanical efficiency=MA of spur gear ×MA of worm gear

Input torque= Output torque/MA

Output torque=Input torque ×MA

Efficiency%= (Output torque ×100)/(Input torque ×Gear Ratio)

Overall Efficiency%=(Spur efficiency ×worm efficiency)/100

Ratio= Number of turns of input/Number of turns of output

Overall ratio=Spur gear ratio×Worm gear ratio

Number of turns to close =Gear ratio/4

Closing time(min)=Number of turn to close/Input speed(RPM)

Closing time(sec)=Number of turns to close×60/Input speed(RPM)

Input Speed(RPM)=Number of turns to close/Closing time(min)

Number of turns to close=Input speed(RPM) ×Closing time(min)

Input torque=(hand wheel rim effort×hand wheel diameter)/2

Hand wheel rim effort =(Input torque×2/Hand wheel diameter

Hand wheel diameter=(Input torque×2)/Hand wheel rim effort