Skill: Cantilever Carriages to a Sliding Gate
Skill level: 3
Gate Mechanics
Learning Objective
Learn how to correctly position and install cantilever carriages for sliding gates to ensure safe, smooth, long-lasting gate operation. This includes proper alignment, spacing, fixing method, and aftercare.
1. Overview
Cantilever carriages carry the entire weight of the gate and keep it suspended while running smoothly on bearings.
Poorly installed carriages cause:
Wobble, twist, or uneven tracking
Bearing wear and premature failure
Gate jamming or noisy travel
Excess stress on the frame and motor
Safety risks if the gate binds or derails
This is a precision job: the carriages must be upright, aligned, well-fixed, and greased for long-term operation.
2. Tools & Materials Required
Cantilever carriage pair (confirm correct model stamped on frame)
Drawing or specification
Steel base plates (if not pre-welded)
Studding/bar, nuts, washers (M12–M16, per carriage spec)
Chemical resin fixings (chem fix), 250 mm minimum depth
Spanners and sockets
Drill with long SDS bits
Hole blower
Template
Tape measure, marker
Spirit level (digital preferred for vertical checks)
String line
PPE: gloves, safety boots, safety glasses
3. Before You Start
Identify the carriage model — always note this in job records for future replacements.
If replacing carriages, measure and record existing positions before removal.
For new installs, use the gate drawing or template to determine carriage spacing.
Allow 150–200 mm clearance at both ends of the run for end stops.
Ensure site ground is solid, flat, and suitable for resin anchoring.
Confirm minimum 50 mm clearance under the base plates when installed. This allows for adjustments later.
4. Procedure (Main Process)
A. Mark and Prepare Fixing Points
On already set concrete foundation:
Mark carriage positions according to gate drawing or min 30% of gate length apart. So a 5000mm gate needs carriages 1500mm apart. There needs to be 150-200mm beyond end of wheels to allow space for channel end caps. Use a string line to get alignment with the closing point. Dont worry too much about vertical setting out at the moment as we have plenty of adjustment on this later.
Mark all fixing holes in the centre— do not skip any. The holes in your base plate are oval for adjustment but if you do not keep all your holes marked in the centres then you will not be able to adjust your base plates side to side.
Drill holes 250 mm deep with SDS drill, keeping perfectly upright. See lesson on Chem-fix. Keep the base plate or template in place as you go and put a stud in each hole as you go to ensure alignment of all studs with all holes.
Clean holes and blow out dust, inject resin, and insert studding. Have all 12 of your studs ready to go with the lower nut in place already. Rest the base plate over the located studs to hold them in place while they set.
Allow full cure before proceding any further.
An alternative method is to do this before your foundation is concreted by creating a plywood or steel template in advance and marking it out accrately, drilling 16mm holes in the correct base plate loactions. You can then use this template to bolt the top of all your studs into, weld or bolt a washer at the bottom of each stud and sink them all together into the still wet concrete so that the concrete sets around your perfectly located studs. If you are confident that this can be done properly it can save a lot of time later.
B. Install and Align Carriages
Place carriages over studs with washers and nuts top and bottom.
Use one nut above and one nut below each baseplate for easy adjustment. Just hand tight for now.
Check with spirit/digital level — carriages must be 100% upright.
Adjust height and level across both carriages so gate sits flat along full run.
C. Final Setup and Greasing
Use caution here. You should have a motor-side goal post fitted already before proceeding. Althouth the top roller may not yet be fitted so take great care not to damage yourself, your gate or goal post.
Fit your gate channel (and gate if it's attached) and adjust height/alignment a little at a time ensuring you adjust each nut the same each time to maintain level. ie turn all top nuts anticlockwise 1 full turn on one base plate, then do all the nuts on the base plate one turn, systematically ensuring that they remain level. If possible use the gate in it's lightest version, ie don't clad it until afterwards.
Once aligned, tighten nuts evenly on all studs.
Whatever you use for a top channel guide can now be secured.
Pump in at least one full 400g tube of grease into the gate channel — grease must reach all bearings.
Confirm smooth travel of the gate over the carriages.
Ensure you fit the travel stops to the channel to prevent the gate coming off the ends! We use stops in the top and bottom channels and weld them in for added security.
If you have a lot of space under the bases, between bases and foundation, you can top up the concrete by a couple of inches to help stabilise the studs and prevent the gate twisting but generally it's not needed as 12off 16mm studs are pretty strong on a 5m wide gate. If you do want to do this then wait until the motor is fitted as you may also want to stabilise this. Ensure you still leave space for later adjustments.
5. Best Practices
Always log the carriage model in Clik/Appsheet for service records.
Studs can be heated up with a heat gun before fitting to reduce cure time.
Leave nuts below baseplate to allow height re-adjustment in future.
Space carriages carefully to balance support across the gate span.
After install, run the gate open and closed multiple times before commissioning.
Re-grease carriages annually or per maintenance schedule.
6. Common Mistakes to Avoid
🚫 Skipping stud holes — all fixings carry heavy load.
🚫 Carriages out of plumb — even slight lean causes tracking failure.
🚫 Forgetting clearance for end stops.
🚫 Fixing with nuts only above the plate — no adjustability.
🚫 Omitting grease — bearings will seize, leading to costly repairs.
🚫 Not recording carriage model for future spares.
7. Safety Information
Always wear gloves, boots, and eye protection when drilling and handling steel.
Ensure the gate is fully secured before attempting carriage installation.
Keep hands clear of rollers when moving gate into position.
Use chemical resin in well-ventilated areas and follow curing times.
Refer to SSOW-15: Installing Cantilever Carriages for the full Safe System of Work.
