The drive gives your stone its speed: backswing from the hips, stone kept ahead, push from the legs, plus cadence, milestones and the most common mistakes.
The honest answer: your stone's speed comes from the drive, not the arm. Curling Canada defines the drive as the first moving phase of the delivery: it begins when the body is set into motion and ends when you leave the hack [1]. The key is staying "connected", meaning body and stone work together as one unit [1].
How hard is it? The movement itself is manageable; the timing is the hurdle. There is no timeline. If you can't yet hold the set-up calmly (see the set-up in the hack guide), stay there first.
Speed matters because you must release the stone before the hog line: if it isn't released in time, it is removed from play [2]. The drive supplies the speed that you then only manage.
Stone and sliding foot move back and forward together, like a pendulum [1]. The cadence formula from a beginner handout: rock back, foot back, park, rock forward, foot forward, slide [3].
Milestone: You run through the cadence ten times without a stone and pause briefly after "park".
The sliding foot goes straight back and straight through, directly towards the target broom [1]. The backward motion is powered by the hips, with an appropriate amount of body weight on the sliding foot [1]. The hips also keep the throwing arm at its angle [1]. The arm stays extended and diagonal to the ice, at least 45° [1].
The stone is the furthest point forward in both directions [1]. It moves straight along the target line without active help from the throwing arm [1]. An initial forward press is allowed, but only short: no more than 2–3 inches (5–8 cm, about a hand's breadth) [1].
Going forward, you shift weight first onto the anchor foot, then back to the sliding foot as it passes the hack [1]. Then you push with the leg drive the shot needs [1]. The heavier the shot, the later you start the push [1]. For draws and light hits you don't need to lift the sliding foot off the ice [1].
Milestone: Three of five stones reach the hack at the far end without you needing your hand.
The shoulders stay square to the target line and level [1]. Hold the broom exactly where it was in the set-up [1]. Handle position (10 or 2 o'clock) and pressure (4–6 out of 10) stay the same [1].
When the shot gets heavier, what changes isn't what you do but when. In elite curlers, the push-off in takeouts was clearly faster and shorter than in draws [6]. That fits the national coaches' rule: push later on heavier throws [1]. So don't practise "pushing harder"; practise "letting the moment shift".
The drive is the first moving phase of the delivery: it begins when the body is set into motion and ends when you leave the hack [1]. In this phase the speed for stone and body is created, and both stay connected [1].
How much swing you need depends on the shot. According to Curling Canada, the sliding foot only goes straight back and straight through [1]. For draws and light hits you don't need to lift the sliding foot, but for hard hits and peels the step is worth it [1]. A beginner handout gives the cadence [3].
That is a timing sign: your body is ahead of the stone [3]. Extend your arm before leaving the hack, and imagine the stone pulling you out of the hack [3]. The stone should be the furthest point forward [1].
The stone must be clearly released from the hand before the hog line at the delivery end, otherwise it is removed from play [2]. A stone that hasn't reached the tee line at the delivery end may be returned and redelivered [2].
Skip Signals in Curling: Placing the Broom and Calling the Shot