I had used information from Detroit region SCCA in building our original system but that info can no longer be found easily.
For rallycross timing, we use a Farmtek timing system with Wireless Handswitch’s modified by Farmtek to have the 2 wires for the normal open contact switch in the box exit the box to be connected to the external pneumatic switch as the trigger. You can call Farmtek and request these switches wired for external switch with a whole system or separately if you already have a Farmtek Polaris Timer Console. The Wireless Handswitch is a Normal Open type of switch. To increase the usable range, we connect a Yagi Antenna to the switch in place of the short antenna and aim towards the Timer Console. I believe these were purchased from Farmtek. Other timing systems may use a normal closed switch. The original switches I used had the option of N/O or N/C depending on wiring. They had a higher failure/inconsistent rate than the AS32WB. I do not see them available with a quick web search.
Pneumatic switch components:
2 each Red-Dot/Master Signal part number AS32WB, Master Signal Air Switches N/O W/Alum, Box. https://www.kleen-ritecorp.com/p-979-ma ... m-box.aspx
2 each Hopkins 47965 2 pole Flat Extension (12") or equivalent. https://www.ruralking.com/hopkins-towin ... set-47965
2 each Home Depot part number 90661 1/2 in. Service Entrance (SE) Water tight Conduit Connector no clue how long this Home Depot link will last
8 each wiring butt splice connectors of your choice.
Electrical tape, heat shrink tubing or RTV to seal the extra area of the water tight conduit connector. Your choice. Sealing the connector will help prevent dirt and debris getting between the contacts of the Air Switch. Dirt there will give you no trigger incidents and lots of reruns.
Cut the 2 pole flat extensions in half. Giving you 4 each, connector pig tails. Each Master air signal and Farmtek Handswitch gets a pig tail connected to their respective bare wires with the wiring butt splice connectors being sure to route the wires through the water tight conduit connector and sealing it up. Color coding does not matter,
Airline components: To be updated with part numbers and details at a later date.
60' of 3/8"ID x 5/8" OD Driveway Bell Hose. Cut these in 20' lengths. 2 will be used for the start and finish, the third will be kept as a spare that you will never need unless you don't have it then a car will cut a start/finish hose. You can choose a different length of bell hose depending on how wide your start and finish gates are.
2 each 12.5-25' 3/8" x 5/8" air hose. This hose is used to run the airline farther away from the course to protect the timing triggers. High Visibility colors help. PVC hose is a pain to deal with on cold days.
4 each 1/4-20 stainless eye bolts. Drill and tap the 3/8" air fitting plugs to fit or JB Weld into a barbed fittings. Used to hold one end of the bungee cords.
2 each 3/8" air hose plugs. Used with the 1/4-20 eye bolt and bungee to hold down the far end of bell hose
2 each 3/8" air hose T fitting. Used to anchor the close end of the bell hose with the 1/4-20 eye bolt with bungee, and also routes the air pressure signal pulse to the air switch via the normal air hose extension.
4 each 18" to 24" rubber bungee. Used with the long eye bolt anchors to provide tension on the driveway bell air hose. Do not pull the hose too tight
4 each 8-12" stainless eye bolts or tent stakes. I prefer the stainless eye bolt with a sharpened tip as the metal hooks of the bungee can be closed around the eye bolt and the entire system is connected end to end. No loose parts. No worries of tent stakes getting lost in the rally cross field to be found at a later date by a punctured tire.
Pack of 10 hose clamps.
2 each heavy duty storage totes. Pile up each assembly of hoses and air switch separately. Buy 2 totes accordingly. Works great to run hose into tote and keep the electrical components more clean and dry.
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