Page 28 - Commercial Vehicle Engineer - September 2021
P. 28

 Moreover, Danfoss Power Solutions uses the same components for the centralised locking mechanism, through their non-
teeth sections. As highlighted in the image
on the previous page (by red arrows), when couplings are pressurised in Multi-FF, the top plate tends to get separated from the bottom plate, which transfers the load to the rack and, in turn, to the pinion via frictional contact.
By using same components for guiding and locking, overall system size remains small. Danfoss Power Solutions manufactures
various Multi-FF components, like top/ bottom plates and handle parts, from aluminium as the lightweight nature of this material improves operator comfort. To attain balance between system performance and weight, the company only uses carbon steel for load-bearing components.
Ergonomics is all about the man-machine interface, namely bringing the machine
to the man intuitively. For systems like Multi-FF, which inherently reduce human effort, it is essential to ensure easy and comfortable operation. Danfoss Power Solutions' Multi-FF offers a combination of features that take care of human ergonomics and provide safe operation.
For example, the handle only requires a short 130° rotation to make a connection and has distinctive start and end positions. As a result, the operator does not have to maintain the handle in position manually
while connecting the top plate assembly with the bottom one. Fixed handle positions, along with operating instructions marked on the system make for intuitive operation. In addition, the system emits a distinct sound at the end of handle rotation to indicate a complete connection. A small collar on the right side of the fixed plate houses these features, again helping to retain compact overall dimensions and maintain a pleasing aesthetic.
The collar features elliptical grooves on its internal surface that act as a guideway for pins assembled on the fixed plate and maintain rotation of the handle within its
specified limit. The highlighted region of the groove (see image below) maintains
the handle in its disconnected state, with the help of a spring-loaded pin. A specially designed profile in this region safeguards against the handle falling from its position, while at the same time ensuring only minor force is required to initiate rotation for the desired connection. A second groove on the collar serves as a positive stop for handle rotation, so it only moves through the defined angle.
The Multi-FF coupling design features a two-layer safety mechanism to prevent any accidental disconnection. At first, in the connected state, gear teeth on the rack and pinion are disengaged as described earlier. As a result, even if pressure tends
to move the top plate upward, the pinion will not rotate and, in turn, Multi-FF will
remain in the connected state. Second, when Multi-FF is fully connected, the
spring-loaded pin gets engaged in the side collar, blocking any further
handle rotation. For disconnection of the system, the operator only needs
to push the red button on the side face, which requires very little effort, and
rotate the handle in the reverse direction. The special design of the red button means there is no space to pull it mistakenly, or for operator injury to occur. Moreover, the
Individual QDC
Multiplate-4x12FFCUP Individual QDC-FFCUP Multiplate-4x12FF Individual QDC-FF
Time required for connection of 4 lines
       0 5 10 15 20 25 TIME, S
Force to connect-comparison for 12FF
  All 4 lines connected together
All 4 lines connected together
Force required for each line
            Force required for each line
  0 50 100 150 200 250 300 350
   The groove maintains the handle in with the help of a spring-loaded pin
its disconnected state,

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