Gruemer Overrun Braking Systems and Trailer Components

Comprehensive technical selection of replacement parts for Gruemer trailer overrun brake assemblies, hydraulic shock dampers, drawtubes, and mechanical linkages.

Grümer AK Series Overrun Braking Devices

Overrun brake assemblies across AK 0908, AK 1308, AK 2008, and AK 3510 series are engineered for utility and commercial trailers up to 3500 kg. Available in tubular and V-chassis configurations, these units transfer deceleration force directly to wheel brake cables.

Durable steel housing with anti-corrosion finish for rigid trailer frame mounting
Precision round drawbar tube with standardized mounting for ball hitch couplings
Hydraulic overrun damper providing smooth braking response and shock absorption
Pivoting transmission lever linked to wheel brake cables for balanced deceleration

Grümer AKP Series Heavy-Duty Overrun Units

Heavy-duty overrun hitches across AKP 1311, AKP 1813, and AKP 2720 series are engineered for demanding commercial trailer applications. Features include grease lubrication points, a reinforced drawtube, and an integrated handbrake spring energy accumulator mechanism.

Reinforced drawbar tube with high torsional rigidity for heavy-duty freight trailers
Dedicated grease nipples for simple and periodic maintenance of sliding bushings
Integrated spring energy accumulator securing reliable parking brake engagement
Dual protective seals guarding internal sliding components against road debris

Grümer APR and APRS Series Overrun Systems

Overrun brake units across APR 1311, APR 1812, APRS 1812, and APR 2720 series are widely installed on recreational campers, Westfalia trailers, and horseboxes. The APRS variant includes a mechanical reverse lockout to prevent brake lockup when reversing vehicle units.

Mechanical reverse lockout mechanism ensuring smooth backward trailer maneuvering
Optimized transmission pivot geometry delivering balanced wheel braking response
Durable sliding bushings produced from wear-resistant bronze or polymer alloys
Steel breakaway cable assembly triggering emergency braking upon hitch separation

Grümer APV Series Square Drawtube Overrun Units

Overrun devices in the APV series are designed for mounting on 70x70 mm and 80x80 mm square drawbars. The square sliding profile eliminates rotational twist of the hitch coupling, ensuring directional stability and rigid alignment during high-speed highway transport.

Square drawtube geometry in 70x70 or 80x80 mm profiles preventing axial twisting
Bolted mounting flanges matching standard transverse drillings on trailer beams
Low-friction flat sliding guides maintaining smooth sliding action without play
Formed elastomeric gaiter sealing internal sliding guides from rain and dust

Grümer Overrun Hydraulic Dampers and Bellows

Hydraulic shock absorbers and gas-oil dampers for Grümer overrun units smooth out braking transitions and eliminate abrupt shocks between vehicle and trailer. Oil-resistant elastomeric gaiter bellows shield the polished drawtube surface from grit and corrosive road grime.

Dual-acting hydraulic dampers with heavy-duty eyelets for pivot pin mounting
Exact dimension matching by compressed length, extended stroke, and Newton rating
Multi-fold flexible rubber bellows with dedicated retaining steel clamp bands
Elastomer compound engineered to resist seasonal weather changes and road salts

Grümer Handbrake Levers, Pull Rods, and Bushings

Mechanical linkage components for Grümer systems include parking brake hand levers with ratchet teeth, cable equalizers, clevis joints, and replacement sliding bushings. These parts restore original mechanical geometry and reliable braking balance across trailer axles.

Handbrake levers with push-button release and hardened multi-tooth ratchet sectors
Precision sliding bushings with low-friction coatings for trailer body pressing
Brake cable balance equalizers distributing equal tension across left and right hubs
Threaded brake pull rods and clevis pins for fine pad-to-drum clearance adjustment

Operational kinematics of trailer overrun braking mechanisms

Grümer overrun braking mechanisms deliver proportional trailer deceleration utilizing the kinetic inertia of the towing combination.

When the towing vehicle brakes, the trailer coupling pushes against the towing hitch ball, generating an axial compressive thrust against the internal sliding drawbar tube.

This linear movement is transmitted through a pivoting two-arm reversing lever directly to the central brake linkage pull rod and wheel brake cable equalizers. An integrated hydraulic damper absorbs sudden pressure peaks, smoothing out harsh impulses during starts and stops.

Balanced return springs maintain steady highway tracking and eliminate unwanted trailer sway.

Inspection and wear assessment of sliding bushings and drawtubes

Prolonged transport over uneven road profiles induces continuous mechanical wear across the sliding guide bushings of the overrun assembly.

Primary indicators of excessive wear include excessive radial play of the drawtube, noticeable clunking noises upon acceleration, and delayed wheel brake engagement. Technical inspection involves measuring the drawtube outer diameter with a micrometer and evaluating internal bushing ovality.

If galling, corrosion pitting, or scoring grooves appear, the drawtube requires prompt renewal alongside its matching low-friction sliding guide sleeves. Proper clearance maintenance prevents binding and ensures predictable vehicle handling.

Selection criteria for hydraulic overrun shock absorbers and dampers

The internal hydraulic damper represents a vital safety component that dampens longitudinal thrust oscillations during trailer pushing and pulling cycles.

When hydraulic fluid leaks or piston seals deteriorate, the damper loses its resistance profile, resulting in harsh banging shocks upon every deceleration event.

Accurate replacement sizing requires verifying overall compressed length, extended stroke, mounting eyelet diameters, and nominal Newton force ratings. Installing an incorrect resistance rating disrupts brake shoe application timing and accelerates mechanical wear on coupling components.

A correctly matched damper restores smooth braking response.

Service requirements for APRS reverse lockout braking assemblies

Overrun devices in the APRS series and automatic reverse variants feature dedicated reverse lockout mechanisms that disengage wheel braking force during backward motion.

When reversing a vehicle combination, continuous backward thrust compresses the drawbar tube, which would otherwise lock the drum brake shoes against the rotating wheel hubs.

In APRS units, an internal cam or disengagement lever mechanism automatically relieves brake cable tension when wheel drums rotate backward. Routine servicing requires checking free pivot movement, removing accumulated grime, and applying water-resistant grease.

Correct adjustment prevents lining overheating while reversing.

Protective elastomeric gaiters and environmental sealing

The precision ground drawtube and forward sliding sleeve remain continuously exposed to road grime, gravel, grit, and corrosive winter deicing chemicals.

Flexible elastomeric bellows (Faltenbälge) form an impenetrable protective barrier around the sliding surface, preventing abrasive wear and moisture ingress. Regular technical inspections check for rubber hardening, surface cracking, and secure retaining clamp tension.

A damaged bellows allows road contaminants to wash out lubricant from sliding bearings, leading to rapid component scoring. Installing a new durable rubber boot with stainless steel clamps maintains operational longevity.

Handbrake lever linkages and cable tension balancing

The mechanical parking brake linkage on Grümer systems comprises a ratcheted hand lever, spring energy accumulator, and cable balance equalizer. Proper linkage calibration ensures dependable trailer holding performance on steep gradients and synchronized shoe engagement across both axle sides.

Threaded adjusting sleeves allow technicians to compensate for natural cable stretch without dismantling wheel brake drums. The ratchet tooth sector and thumb release button must engage cleanly without binding or slipping under heavy tension.

The steel emergency breakaway cable triggers instant parking brake activation if accidental uncoupling occurs.

Gruemer and model names are trademarks of their respective owners and are used only to identify the equipment for which we source parts. SpareX is not an official dealer, distributor or representative of Gruemer and is not affiliated with the trademark owner. Origin, documents and warranty are stated for each item in the quotation.