June 2021
Installation, Operation and Maintenance Manual
MAN 689 Rev. 6
Figure 26
Scotch Yoke Mechanism Heavy Duty Version
Table 17.
Parts list
Item
Qty
Description
Material
1
2
O-ring
* NBR rubber
2
2
Yoke bushing
Carbon steel
3
2
Washer
Stainless steel
4
1
Housing
Carbon steel
5
1
Guide bar
Alloy steel
6
1
Yoke
Carbon steel
7
1
Cover gasket
* SBR + Cel Fillers
8
1
Guide block
Carbon steel
9
1
Bushing
Steel + fiberglide
10
2
Sliding block
Carbon steel
11
1
Vent valve
* Stainless steel +
fluorosiliconic rubber
12
12
Screw
Carbon steel
13
1
Cover
Carbon steel
14
1
Guide block pin
Alloy steel
16
2
Screw
Stainless steel
17
2
Yoke supporter washer
Ertacetal
18
2
Yoke bushing seat
Steel +
fiberglide
19
2
Guide block pin bushing
Steel +
fiberglide
20
4
Sliding black seat
Steel +
fiberglide
21
2
O-ring
* NBR rubber
NOTE:
* Recommended spare parts
* Cycles perfromed by actuator in a 25 years expected lifetime - The minimum performed cycles
are guaranteed by Biffi based on service conditions listed:
- All the valve required torques have to be lower than actuator max operating torque (MOT)
- The ration between valve required running torque and actuator max operating torque (MOT) has
to be >1,5.
- The actuator mechanism has to be inspected, lubricated, seals and gaskets have to be replaced
after each 200,000 cycles.
46
Layouts and Sectional Drawings
Section 8: Layouts and Sectional Drawings