Selecting a Transmitter

Which RC system to use depends on the functionality of the model. Most models will have servos to mechanically lift the snow blade, and eventually also for the nick function (cutting angle). For such models a "normal" RC-system is absolutely sufficient, these are available from many vendors und relatively cheap.

But if you want to implement hydraulics for all 6 functions of the snow blade you will quickly reach the limits of these RC systems. We tried a level-switching module, which was not successful as the control valves could not be adjusted individually. Here you have to reach deeper into your pockets and acquire a specific RC-system for functional models.

We are using both systems, for our mechanically controlled models we decided to use the HiTec Aurora 9 or the Aurora 9X due to the following reasons:

- 9 channels

- flexible programming

- user friendly, large touch screen display

- expandable telemetry functions - the receiver battery voltage is shown by default on the transmitter

- rather low price for the available functionality

For our hydraulically controlled PB400 we acquired the Scaleart Commander SA-1000 with the receiver CM-5000 due to the following reasons: 

- practically unlimited number of channels

- extensive programming capabilities specifically for functional models

- specific hydraulics functions

- telemetry allows complete monitoring of the driving battery

- direct connection of the Pistenking Kingbus light system

The considerable cheaper system of Servonaut was limited to a maximum of 12 channels at that time. This is a few channels short of what is needed for a snow groomer. 

Back-up Lock with Lowered Tiller

An unintentional reverse drive with a lowered tiller should be avoided by all means in order to not damage the tiller. At the big snow cats the tiller is therefore automatically raised or the reverse drive is blocked. The most elegant way is of course to use the Hydromaster AFF from Pistenking which lifts the tiller automatically in reverse drive.

We tried to program an automatic raising of the tiller when driving backwards by using the mixers. But here it showed that the mixers are intended for aircraft models, where only small amounts of control movements have to be added. This approach was not successful. Maybe the mixers can be used for winch operation, but we are not there yet.

But a back-up lock was relatively easy to achieve:

Put the driving function forward/reverse on the throttle channel. This channel is different from all other channels, as it does not go from -100 to +100, but from 0 to 100. Therefore the center position is at 50. This means the snow cat is not moving. The receiver treats every channel the same, and for the speed controller it does therefore not make a difference which channel is used on the transmitter. The Aurora 9 allows a free selection of the throttle channel as well as of all other channels. 

For aircraft different throttle curves may be programmed, like for normal flight or for aerobatics. These are changed by a switch. 

An undocumented advantage of the Aurora 9 is the fact, that switches can be used twice. Here we use switch B (SW-B) at the same time for raising/lowering the tiller and for changing the throttle curve. 

The pictures show the different throttle curves: for switch SW-B in position 1 (tiller up) the throttle curve is linear from 0 - 100: the snow cat can be driven as usual. For SW-B in position 0 (tiller down) the throttle curve is at 50% for the entire range of the control stick from center to rear position. This means that the snow cat cannot move backwards, because this is the zero position for the speed controller:

Only if the tiller is raised the throttle curve is switched to the regular curve and the snow cat is again driveable without restrictions.

Such a programming of a throttle curve can certainly be done on other programmable transmitters, too. But we don't know if you are able to use just one and the same switch for lifting the tiller and for switching the throttle curve. But exactly this feature enables the desired operating safety.