Curtainsider Trailers Engineered for Operational Value

Built for Value, Reliability and Real-World Operation

Don-Bur curtainsiders are designed for operators who prioritise long-term value over short-term cost. Every trailer is engineered to deliver dependable daily performance, withstand intensive use and integrate cleanly into fleet operations. Our approach centres on understanding the duty cycle and building a solution around it — not forcing a standard product into a specialist task.

This means the chassis, bodywork, load restraint and access systems are configured to match how the trailer will actually be used: the type of freight, site constraints, handling equipment, route profile and required service life. The result is a curtainsider that performs reliably from day one and continues to add value throughout its working life.

Don-Bur’s commitment to engineering-led design, proven durability and attentive aftercare has earned long-standing trust across national fleets, regional operators and specialist sectors. Whether your priority is maximising internal cube, improving loading efficiency, handling dense or irregular freight or enhancing fuel performance through aerodynamics, each curtainsider is built to meet a clearly defined operational requirement.

Below is an overview of the core design principles that underpin a Don-Bur curtainsider, followed by detailed sections covering load security, durability, flooring, configuration options and safety systems.

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Quality & Durability

Providing peace of mind

EN 12642-XL

EN 12642-XL is the recognised European standard for whole-body load containment. For curtain-sided bodywork, it defines minimum structural resistance and acceptable deformation under forward, rearward and lateral loading. These tests verify that the body contributes to stabilising correctly positioned freight during normal road transport.

All Don-Bur curtainsiders are built to EN 12642-XL as standard. This provides operators with a documented and independently verified level of structural performance without needing to specify the rating as an optional extra.

XL rating does not remove the need for appropriate load restraint, but it provides a proven containment baseline. In the UK, the DVSA accepts EN 12642-XL as supporting evidence of adequate load containment when freight is positioned to achieve positive fit, reducing reliance on additional lashings for many palletised goods.

For mixed or general haulage fleets, specifying XL-rated curtainsiders helps maintain consistent load-security practice across varying routes and loading points and provides predictable handling characteristics for the driver.

Load Restraint Options

Safe transport depends on selecting restraint equipment suited to the freight, vehicle type and operating environment. Curtainsiders rely on positive-fit loading supplemented by suitable restraint systems to minimise movement during normal driving conditions.

EN 12195-2 compliant rave-to-rave webbing straps: Widely used for stabilising palletised goods across the full trailer width.
Roof mounted straps: Roof mounted straps suitable for loads up to 400kgs
Transverse nets (kites): Useful for limiting forward or rearward movement of mixed or lighter palletised loads.
Side nets: Assist with controlling lateral movement of irregular freight or part loads.
EN 12640 lashing points: Factory-tested anchorage points for attaching straps or chains where item-specific restraint is required.

These systems complement XL-rated bodywork but do not replace correct load positioning. Loads should be arranged to achieve positive fit wherever possible and restrained according to the type of freight and expected route conditions.

Everyone involved in loading a vehicle or managing a transport operation is responsible for making sure the load is: safely loaded, secure during transport, safely unloaded

DVSA – Securing loads on HGVs and goods vehicles

See our load restraint feature library

Durability and Corrosion Protection

Long-term service life is a core design consideration. Don-Bur chassis units use a heavy-duty all-bolted construction and are commonly specified with localised galvanisation to protect against road spray, salt and weathering. Reinforced cant-rails, robust crossbearers and high-wear components withstand repeated forklift side loading and high utilisation across varied routes. Additional options such as stainless-steel hardware, reinforced wear bands and high-grade curtain fabrics extend service life and reduce maintenance frequency.

Flooring Options

Floor specifications are matched to duty cycle and loading method. Options include Keruing hardwood planking, phenolic-coated plywood and even omega steel reinforced flooring and sacrificial flooring overlays. Reinforcement can be added for concentrated forklift axle loads.

Additional anti-slip surfaces, rear steel "dump" plates and local strengthening are fitted where required.

Aerodynamic Specifications

Teardrop body profile for improved airflow.
Side skirts, bulkhead deflectors and roof diffusers.
Rear boat-tail configurations for trunking operations.

"Improving the aerodynamic performance of heavy goods vehicles (HGVs) has been identified as one of the measures that can be introduced to reduce a vehicle’s fuel consumption and its carbon dioxide (CO2) emissions."

DfT – Guidance

Rear Closure Options

Rear access can be configured with container doors, flush-fit barn doors, roller shutters or simple fixed panels. Enhanced sealing and optional TIR capability can be integrated for routes requiring added security or cross-border conformity.

Learn more about closure options

Branding and Livery

Don-Bur has it's own in-house "Sapphire" graphics division providing full branding and livery options including printed curtains, vinyl graphics and operational decals.

These support fleet identity, marketing messages and operational compliance.

Common Configuration Options

Beyond the core engineering choices shown in the specification table, curtainsiders can be equipped with additional operational features that support specific duty cycles, loading methods and fleet practices. These options do not change the structural specification but influence usability, efficiency and safety.

Bulkheads and internal partitions – used for multi-drop, mixed-load or segregated freight operations where loads need containment or division during transit.
Toolboxes and storage solutions – including strap-stowage systems, wheel chocks and ferry/RoRo equipment, selected according to site procedures and driver requirements.
Moffett Mounty mounting kits – fitted where self-offloading capability is required, typically on regional distribution or construction-related routes.
Enhanced security features – such as reinforced or anti-slash curtain materials, PIR intrusion detection, telematics-based curtain monitoring and TIR-capable rear closure systems for high-value or cross-border cargo.
Lighting and visibility upgrades – supplementary LED work lamps, high-visibility brake strips or additional marker positions to improve night operations and depot safety.

Curtainsider Trailer Specification Matrix

The following overview summarises the main specification areas available on Don-Bur curtainsider trailers and the engineering factors that typically determine each selection. All trailers are designed to individual operator requirements.

Further options are available.

	Typical Options	Engineering Notes
Body Height / Aperture Height	Typical overall heights range from: • ~3.60 m (urban delivery) • 4.00 m (European maximum) • 4.20 m (common UK height) • 4.50 m ("tall boy" high-volume builds) • Up to ~4.95 m (maximum) Side and rear aperture heights vary accordingly.	As a rule of thumb, apertures on straight-frame chassis are calculated as: aperture height ≈ overall height − 1550 mm. For example, a 4.00 m trailer typically achieves a side aperture of approximately 2450 mm. Slimline neck designs and slimline cant-rails can increase aperture height further by reducing structural depth without compromising strength.
Length	Length is fully configurable and depends on route type and operational geometry. Typical ranges include: • 13.7 m (standard UK semi-trailer) • Up to 15.650 m for LST-compliant designs • Reduced lengths from ~8 m for urban, tight-access or multi-drop operations	Length is determined by the operating environment, turning-circle requirements, tractor compatibility and desired internal volume. Shorter bodies improve manoeuvrability in congested or restricted sites, while LST configurations maximise payload and cube on trunking routes where regulations allow their use.
Wheelbase (Kingpin → Axle Centreline)	• Up to ~8.100 m on standard 13.7 m trailers • Shorter wheelbases for reduced-length or urban builds • LST configurations typically incorporate a steer axle	A wheelbase of up to ~8.135 m meets the UK “deemed to comply” turning-circle rule for conventional 13.7 m tri-axle semi-trailers. Shorter trailer bodies use reduced wheelbases to maintain manoeuvrability and axle-load balance. LST designs require more complex arrangements and generally rely on steer axles to achieve mandated turning-performance requirements.
Axle Type	BPW, SAF or JOST; drum or disc brakes; optional lift/steer	Based on fleet standardisation, maintenance planning and route-specific handling or weight-transfer needs.
Wheel Size	Wheel and tyre combinations typically include: • 17.5" twins (small diameter) • 19.5" twins or mini-singles • 22.5" super-singles (e.g. 385/65 R22.5)	Tyre diameter has a direct impact on rear bearer height and therefore achievable internal cube. Smaller 17.5" twin wheelsets can result in bearer heights of ~880 mm, maximising internal height. Typical 385/65 R22.5 super-singles produce bearer heights around ~1250 mm, balancing cube, stability and durability. Selection depends on load type, desired internal height, running-cost considerations and fleet standardisation.
Braking System	Haldex, Knorr-Bremse or Wabco (ZF); optional EBPMS	Configured to operator preference, compliance requirements and integration with fleet telematics or maintenance reporting.
Coupling Box Type	Fixed coupling box, sliding coupling, double sliding rail, LowGlide safe ground coupling	Driven by tractor variations, coupling frequency and required safety standards.
EN 12642-XL Required	XL-certified bodywork as standard	Provides recognised whole-body load containment and aligns with DVSA expectations for positive-fit loading.
Rear Closure Type	Container-style doors (single or double locking bars), wide-lath roller shutters, fixed panel	Selected based on access method, required security level, load type and depot handling equipment.
Internal Load Restraint	Rave straps, roof-mounted straps, nets, side nets, EN 12640 lashing points	Chosen according to freight stability, load positioning, multi-drop patterns and regulatory expectations.
Floor Strength	Hardwood, phenolic ply, reinforced steel sections; variable cross-bearer pitch	Matched to maximum forklift axle point loads (with FOS) and expected abrasion or impact exposure.
Lighting Options	LED markers, combined indicator/marker lamps, rear cluster bulb/LED units, stalk markers, high-visibility brake strips, work lamps	Configured to visibility standards, night-time operations, health & safety requirements and operator preference.
Aerodynamic Enhancements	Teardrop profiles, side skirts, diffusers, boat-tail	Specified for trunking routes or fuel-saving programmes; site clearance and operating speeds are key factors.
Safety Options	Leg-Safe, LowGlide, EBS-Safe, VRU detection systems, PIR sensors	Added to mitigate operational risks, improve loading safety and support internal fleet safety policies.

FAQs

Do curtainsiders need to be EN 12642-XL rated?

EN 12642-XL is not legally mandatory, but it is widely specified because it provides recognised whole-body load containment performance. When loads are positioned to achieve positive fit, XL certification helps operators meet DVSA load-security expectations without relying solely on additional lashings for most palletised goods. All Don-Bur curtainsiders are built to EN 12642-XL as standard, providing a consistent and verified containment baseline across the fleet.

What does positive-fit loading mean?

Positive-fit loading means positioning freight so that it is held firmly against fixed structures with minimal free space. As a general guide, loads should be placed within 300 mm of the front bulkhead or rear closure and within 80 mm of the trailer sides, with no gaps between adjacent items within this zone. Maintaining positive fit reduces the potential for load movement during transport and is a key principle used in EN 12642-XL testing and DVSA load-security assessments.

How can I increase the durability of the curtains?

Curtains are wearable items, but longevity can be improved. Internal wear bands reduce abrasion from loads, top-mounted double rollers improve smooth sliding and reduce tension build-up, and UV-stable printed curtains retain colour for longer even with frequent cleaning. Ensuring that loads are positioned accurately and avoiding unnecessary contact with sharp edges also helps extend curtain life.

What load restraint systems are typically used in curtainsiders?

Common systems include EN 12195-2 compliant rave-to-rave webbing straps, transverse nets, side nets and EN 12640 lashing points. The correct method depends on load type and whether positive-fit loading can be achieved. These systems supplement, rather than replace, the containment provided by EN 12642-XL bodywork.

Which safety options are commonly specified?

Popular options include LowGlide, Leg-Safe, EBS-Safe, Direct Vision enhancements and vulnerable road user detection systems. These features support safer coupling, loading and urban operation while helping operators meet internal fleet safety policies and reducing the likelihood of avoidable incidents.

Finance Options

Finance can help operators align trailer investment with fleet replacement cycles or planned operational growth. Many fleets prefer structured payment schedules to support predictable budgeting and to introduce new equipment without significant upfront capital outlay.

Don-Bur works alongside established funding partners who understand commercial vehicle operations. This enables operators to explore lease or purchase arrangements that suit their own financial strategy and duty cycle.

Learn more about finance options