Document

Report
Tomislav Skračić, MA
Undergraduate English
Course for
MARINE ENGINEERS
4th Semester
Essential reading:
SPINČIĆ, A., PRITCHARD, B., An English Textbook For
Marine Engineers 2., Pomorski fakultet, Rijeka 2009.
LUZER, J., SPINČIĆ, A., Gramatička vježbenica engleskog
jezika za pomorce, Pomorski fakultet, Rijeka 2003.
Lesson 8
VALVE OPERATING GEAR
Lesson 8
Valve Operating Gear
KEY WORDS
valve operating gear
times in the cycle
push rod
train of gears
chain drive
keyed on
bolted together
follower (n.)
hinged follower
sliding follower
- ventilno polužje za pokretanje ventila
- momenti kružnog procesa / ciklusa
- spojna motka, podizač
- niz zupčanika
- lančani prijenos
- učvršćen / osiguran klinom
- spojen vijcima (danas se koriste
SKF couplings - spojke na principu smicanja)
- vodilica, podizač (usp. 'roller guide')
- zglobni podizač brijega, "britvela"
- klizni podizač
Lesson 8
Valve Operating Gear
KEY WORDS
lever form folower
tappet form follower
side thrust
fulcrum pin
pivot (n.)
bronze bushing
set screw
lifting rod
idle gear [aidl]
- podizač u obliku poluge
- podizač u obliku cilindra
- bočna sila / potisak
- uporište poluge
- os, hvatište, utorište
- brončana rupa za osovinicu, bukola
- pritezni vijak, podešavajući / regulacijski vijak
za zračnost i sl.
- podizna motka
- međuzupčanik
Lesson 8
Valve Operating Gear
1. DEFINITION
A mechanism for actuating & controlling the inlet and exhaust
valves. It may also open and close air starting valves and fuel
pumps.
2. OPERATION OF VALVES
 Mechanical (valve operating gear)
Exhaust valve operating gear
1. DEFINITION
A mechanism for actuating & controlling the inlet and exhaust
valves. It may also open and close starting air valves and fuel pumps.
2. OPERATION OF VALVES
 Mechanical (valve operating gear)
 Hydraulic. There are neither pushrods nor rocker arms but a
piston pump. The oil pressure is led by means of a high
pressure pipe to a working cylinder and hydraulic piston placed
on top of the exhaust valve cage.
Hydraulically operated exhaust valve (Sulzer)
3. CAMSHAFT
3.1 CONSTRUCTION
Integral camshaft is made in a single piece of forged steel;
Separate cams of forged steel or cast iron are:
 keyed on the shaft;
 hyraulicaly shrunk on or press fitted;
 fitted to the shaft by SKF oil injection pressure method.
3.2 CAM DESIGN
3.3 CAMSHAFT ROTATION
4-stroke = ½ speed of the crankshaft
2-stroke = same speed as the crankshaft
3.4 CAMSHAFT DRIVE
 Train of gears
 Chain drive
3.5 REVERSING
The camshaft slides axially (in 4-stroke engines) thus bringing a
different set of cams for reverse direction.

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