A silage scraper system suitable for scraping silage along a passageway and comprising scraper means (10) adapted to move lengthways along the passageway, actuating means for controlling the movement of the scraper means along the passageway, and a tripping device (1) for modifying (i.e. stopping, or reversing the direction of) movement of the scraper means when it encounters an obstacle. The tripping device (1) comprises a slider (2) mounted within a housing (4) for movement along an axis generally parallel to the movement of the scraper means. At least a proximal end of the slider abuts a resiliently deformable means (5a, 5b). The slider (2) is operably connected to the actuating means such that when the scraper encounters an obstacle and stops suddenly, inertia causes the slider to move and engage the actuating means to modify movement of the scraper means. The resiliently deformable means is generally a helical spring (5a, 5b), which upon movement of the slider (2) biases the slider back to its resting position (Fig. la). The actuating means is a ratchet mechanism (12) which extends along the passageway and is adapted for backwards and forwards reciprocal movement, and a pawl (13) pivotally mounted on the scraper means (10) for engagement with the ratchet mechanism. The slider includes an arm (3) which in a resting position abuts an end of the pawl such that movement of the slider effects movement of the pawl out of engagement with the ratchet mechanism.
